Honestly, Froyo was a huge jump, and then so was Gingerbread (which brought JIT and some other major code/speed enhancements). ICS, aside from some features most custom launchers already offered, was pretty underwhelming. So having the latest Android just isn't anywhere near as exciting as it used to be. I care about developer phones because I run a really heavy home set-up, and without running vanilla Android overlaying my launcher on something like Touchwiz would still cause me issues even with 2gigs of ram. Also piece-of-mind to have a back-up if I soft brick my phone messing around with root.