The young can be conservative too...
..and sometimes it's the flipside to that ability to "lock on" as mentioned above - focussing on something to the exclusion of everything else means just that - excluding other things, ruling out other options.
Of course that's not necessarily a bad thing... (see blissblogger et al's discussions passim on purism, dilletantism, either/ or) .. and of course it often takes you deeper into new territory, faster.
But when you're young you often lock on to something for very conservative reasons - fear of the unknown, for example, the worry that you might be overwhelmed if you step outside your specialist field. The need to limit the choices available in order to make headway. Or ignorance - it's always easier to dismiss something when you don't know anything about it, and when you're young, the chances are there's a lot of stuff you simply haven't had a chance to get to grips with or fit into context.
Surely this is something you lose with age. There's less sense that your tastes define you - it's more the other way round - so you can try on anything for size. It's a lot easier to admit to ignorance as well, when you're fairly confident that in other areas of your life you do actually know something about something, so you have fewer qualms about appearing a total novice. Plus there's - how to put this - a richer texture to your knowledge, which means there are more possible ways that you can fit something new into the scheme of things without having to re-jig the whole thing, and disrupt some fragile emerging identity.
Of course, that may make you old and bland, with a sort of benevolent smiling interest in everything and no focus - although that's not to say that you can't have tastes that are diverse and discriminating at the same time. But being bland isn't the same as being conservative/ narrow minded.
I think that there can be a process whereby early conservatism mellows and broadens its perspective with time. Perhaps for some people the accumulation of confidence and knowledge is actually a necessary first step before expanding their horizons.