Sure, but API concepts introduced in Honeycomb are (hopefully) being propagated through v4.0 and beyond. So apps have to catch up when they move to v4.0. There was a big push to get apps to build UIs which work on phone and tablets, which not many developers adopted because of immense number of bugs in their Compat Libraries. v4.0 is just going to make it worse -- my users are still running 2.2/2.3, so I can't abandon them. And I refuse to maintain multiple code branches.
If you know the details and spend a few minutes thinking about what's involved in making stuff 'just work', you'll realize how painful it is. Google's solution is to let devs release multiple APKs per platform - that is it's own maintenance nightmare (bugs/servicing, testing, dev environments, etc).
I thought Google's solution was to move past that and have ICS run on everything, degrading higher-end functionality gracefully within the OS if it finds itself running on less capable hardware.
For the record, I read "There is a reason Honeycomb adoption is abysmal" as relating to users' adoption of Honeycomb (which seems necessarily linked to adoption of tablets, IMHO much more so than to the amount and quality of third party software available) rather than Android application developers' adoption of Honeycomb APIs (which I'm now thinking might have been your intended meaning, and which obviates my entire post).
