HTC Sense and custom skins in general

Firstly: yes, I do understand why OEMs develop their own Android skins. Differentiation, standing out from the crowd, etc etc. A sometimes regrettable but more or less understandable part of the ecosystem.

Here's what I don't understand: HTC already stands out from the crowd. It's got hands down the best industrial design of any Android OEM. It's up there with Apple and Nokia: I actually think the Amaze is maybe the best-looking phone on the market. HTC has succeeded in differentiating itself from the competition on a purely hardware level in a way that none of the other OEMs have managed to accomplish.

They've also got Sense. That's fine, I'm sure a lot of people walk into the phone store and see a big Gothic clock or an animated weather widget and say to themselves "this is the phone for me!" I'm sure that for most customers Sense isn't a drawback, and that for a significant number of low-information customers it might actually be a plus.

But it's obviously not a plus for technophiles. I know a lot of tech-savvy people, and I consider myself among them, who would love to have an excuse to buy HTC phones. They look great! They feel great! They've got unibody aluminum constructions! But none of us is going to buy a phone whose performance and battery life is crippled by Sense, and whose update schedule is at the mercy of some faceless bureaucrat somewhere in HTC headquarters (or the good folks at Cyanogen, for that matter).

I'm sure HTC understands that it's losing a significant number of first-adopters this way, and an even larger number of first-adopters' parents, siblings, cousins, girlfriends, etc. So why the hell hasn't it done anything about it? Why hasn't it implemented an option in the settings menu to deactivate Sense? Why did it hem and haw for a few days when asked if its current dual-core phones would be upgraded to ICS, instead of immediately declaring that keeping all of its phones on the newest version of Android is a top priority?

I guess a corollary to this would be: if essentially no other phone on the market (except the Nexus line and a few scattered exceptions like the G2x) is running stock Android, wouldn't putting stock Android on your phone differentiate you just as much as saddling it with a custom skin? This applies to all of the OEMs, not just HTC. 

Thoughts? Is there something I'm just not getting about the financial incentives OEMs have to develop their own custom skins? Because it seems like a lot of wasted money and effort in most cases.