The iPad retains the screen rotation lock in 4.2, it's just changed to mirror the way it was implemented on the iPhone when 4.0 came out.

If you want a concrete example of Apple listening to it's users, look at their products. Not many users indicated their interest in the XServe, so it's going away. That may seem bad (and it definitely is for the few groups of people that depended on the system), but it allows Apple to put those resources elsewhere, instead of keeping a near dead product alive and potentially driving up costs elsewhere. There is also the generation of iPod with the weird 4 buttons above the scroll wheel. They received feedback that people generally didn't like that and the generation after was changed back with the click wheel. Some of their pro users indicated a strong liking for non glossy screens, so the 15 and 17 inch systems offer a non glossy option. Those are three examples I can think of, there are probably many more others could point out.

I've submitted, and had feedback responded to regarding Apple's products, so I even have personal experiences to know they do listen. Jobs just happens to be user #1 with a very big override on other feedback. BluRay is sadly one of those frustrating areas where he is overriding my own feedback.

Below are ways I know of to submit feedback to Apple, and at least have it read. It may not be considered or acted upon, but thats most likely the case for many other companies too.

http://www.apple.com/feedback/
https://bugreport.apple.com/