No one is likely to be surprised by the notion that anime is, by and large, made for (if not always by) younger audiences. You don't have to look at the demographics of the audiences themselves to understand this: look at the demographics of the show's casts, which tilt by and large heavily towards the under-20, to say nothing of the under-30 set. But the way anime ignores older characters, or at the very least gives them short shrift, is growing harder to ignore — and not just because I've long since pushed past forty myself.
I'm not going to make the case that characters over the age of thirty (or forty, or fifty) cannot be found in anime. You're more than likely to find such characters, whether their ages are implied (gray hair, grizzled features) or spelled out right in the character file. The question is what roles they inhabit, and whether or not they have a pivotal effect on the goings-on. And too often, older characters are relegated to the backseat, as mere contrast/chorus character, as comic relief, or as second (or third, or fourth) bananas. It's the young'uns who drive the show.
My take on why this is so is because it is a manifestation of the idea that a younger audience will only connect with, can only connect with, characters who are in their age bracket. There is a grain of truth to this, but I submit that there's only a grain of truth — that a young audience can be inspired by and attracted to characters of any age, as long as they are presented in a compelling way. One variant of this argument (I forget where I heard this, but I'm happy to add a citation after the fact if someone sets me straight) involved the U.S. cartoon Superfriends: even when you were a kid yourself, you wanted to see Superman and Wonder Woman do more of their thing without having those annoying kid sidekick characters (inserted for "audience identification", I guess) cluttering up the show.
The idea that people will only connect with a story if there's someone of their age in it is bogus, but bogus in a seductive way. It's the sort of thing that's more credible to advertisers and promoters than it is to actual audience members or creators — and those tend to be the people who exert the most leverage over how a show is put together. As ad dollars have grown scarcer, and anime budgets have been slashed, the average show is being composed in a way that hedges as many bets as possible, and so the cast tilts young as a safety measure. This despite the fact that a sizeable slice of the hardcore anime audience in Japan consists of folks over the age of 30, not the 15-year-olds that many shows fill out there casts with — which brings to mind my theory that they're only apparently designed for audiences of 15-year-olds, but really being designed for audiences of 30+-year-olds who want to feel like they're 15-year-olds.
Don't think I'm trying to argue that it's the target demographic for a show that goes a long way towards dictating its quality — that seinen shows, because their casts tilt older, are inherently better than shōnen or shōjo productions. That's malarkey of its own kind; plenty of shows aimed at older audiences are lousy. What I'm arguing is that a show which takes the time and effort, no matter what demographic it's aiming for, to see and represent a broader range of ages in its characters — and which doesn't succumb to the fiction that the only characters worth investing with true importance are the ones that match its target demographic — is going to be a better show.
When older characters are allowed to climb out of the backseat and come to the fore, it opens up the possibilities for what the show can address and accomplish. Consider Ghost in the Shell: Stand Alone Complex, a show that has become a favorite of mine because it barely has anyone in its entire cast that's under the age of twenty-five to thirty. Many of them are grizzled vets of one variety or another, and one of the most powerful characters in the show, Chief Aramaki (shown in the image up top) is easily pushing sixty. How refreshing it was to discover GITS:SAC and not be offered a single compulsively young audience identification character — and not feel as if we needed one in the first place, either!
Or consider Cowboy Bebop, another show that more than outlasted its initial burst of fandom and went on to become a staple title. I wouldn't say its success is solely due to the cast being on the older side (okay, Ed is basically a kid, but not in the audience-identification mold), but it helped, and gave that noir-tinged space western the gravity, pardon the pun, it needed to be truly effective. But few anime use older characters to make a deliberate point. One of those very few that does come to mind is Katshiro Otomo's Roujin-Z, also designed to make some satirical points about the way advanced societies tend to use their technological sophistication to pack away and ignore the aged and the infirm.
Two anime directors in particular come to mind as good examples of how an adult cast, or a cast of all ages, can expand the scope of what's possible in the medium. The first is Satoshi Kon, whose untimely death grows all the more poignant year after year in light of how the work he chose to do -- Perfect Blue, Millennium Actress, Tokyo Godfathers, Paranoia Agent, Paprika -- was done in spite of what the industry at large was interested in and not because of it. All those movies and shows tilted towards having adult characters, both in the sense of their ages and in the sense of what kinds of problems they grappled with. Those productions were never less than entertaining on their surfaces, and one could come back to them and discover any number of greater depths in them — in part because they were about characters who represented more than just one phase of human life.
The same could be said of Hayao Miyazaki's movies and Studio Ghibli generally. Like the Disney Studios of old, Ghibli is one of the few outfits that truly makes films for all ages. Younger characters do come front and center the majority of the time, but that comes off less as a marketing ploy than as a reflection of the studio's keen understanding of young people as people. But beyond that, I remain impressed with the way the Miyazaki/Ghibli productions bring in characters of all ages and do justice to them. My reigning favorite in this regard now is Whisper of the Heart, where characters from every phase of life — childhood, adolescence, young adulthood, adulthood, and old age-- fill out the cast and contribute each in their own way. The cumulative effect is something like what Roger Ebert mentioned in discussing Fellini's La Dolce Vita: watch the movie at different phases of your life, and it speaks to you in the language of the age you're in, rather than in just one tongue alone.
Some of this, I admit, is all about demographics — who watches what and why, and how their expectations are often shaped by what aired before. Anime is for the most part a commercial product, and sometimes the only way for it to come into existence at all is by being conscious of of how it can reach an audience willing to pay for it. But anime owes it to itself, and audiences of all the ages it reaches, to look beyond the obvious.