One other thing, if Android/Google execs read this: for the love of God go ahead and admit that there is a need for tablet apps . It's the first step in solving the problem - admitting you have a problem. As long as you have the attitude that phone apps work "just as well" on tablets, developers will have the exact same attitude and will not care as much. It also "helps" that you don't really want to emphasize tablet…
One thing they can do is promote good apps, not the way they're currently doing it (e.g. Staff picks, Top developer), but with something like the Apple's approval system, but not to the extreme of "the app is either approved or denied". I was thinking more like the dev can pay a fee to get his app reviewed (UI, performance, ...etc) and when "approved", it gets a symbol (check mark, star, whatever) and put on a category of "approved" apps. This will probably encourage more devs to work more on their apps to get them promoted.