I understand handset makers not providing timely upgrades (who wants to spend engineering/support $s on software upgrades for a sale you already made to a customer [really, a customer of your customer] who probably won't hold any loyalty to your brand either way), but why are so many new devices coming out with really old versions of Android? I've never really seen anything like that before... PC makers are ready to…
Because they spend a ton of money on crap "enhancements" to the original UI (except for HTC sense which I don't really care about, all others I've seen are crap). If they just released plain Android they wouldn't have anything to differentiate themselves. The problem with their plan is that they suck at software development and their enhancements make the phones worse and outdated.
Anyway, here's a radical and not necessarily good idea: what if the base "Android" release didn't have a launcher/etc at all, leaving what's commonly called "the UI" entirely up to handset makers. Sure, spin off the existing launcher as a separate open source project, but make it just one competitor among many. If diversity in this area is good and manufacturers really do want to differentiate themselves, make that a core part of the platform. It's not like it's that expensive to write a launcher.