I've noticed in the past couple months that things are really turning around on this front - many, many apps have updated with new, nice icons. Whereas before I would cringe every time I scrolled through my app drawer, now there are only a few sore thumbs sticking out
Some which are still quite bad include:
A2SDGUI - ugly
androidVNC - the concept for this one isn't bad, really, but the graphic is ugly
Apps Organizer - if you think about what this one is trying to represent it makes sense, but it's pretty boring
ASTRO - I agree with the earlier comments about this. I think it may have changed recently (not sure) but if it did, it hasn't improved. Especially bad because it shows extra icons if you install the extensions (for bluetooth and SMB).
drocap2 - I don't mind this one since the camera looks cool and it doesn't stick out, but it doesn't really suit the app.
ShootMe just updated to a nice new icon; the design is very nice, but I actually wish they kept the pink instead of turning it orange - I think orange complements the android green pretty well, but it's become overused and too much orange is always ugly.
NYC Bus & Subway Maps - this was discussed here frequently and has undergone a lot of fairly recent changes (including the name change); I think there was an icon at one point that I liked but the current one isn't great. I liked the suggestion put forward here, very elegant and fitting.
Ringdroid - conceptually makes sense, just bad design
SetCPU - design is fine, but looks bad (low quality)
Speed Test - they just changed this a couple days ago I think - interestingly, the old one was better IMO. The UI changed for the worse too.
Titanium Backup - yep this one's bad, but, at least it's quite distinctive
Should be pointed out that Google isn't perfect either - these ones I don't like:
Clock - always hated the clock logo
Gallery - always hated this one too
Settings - I really don't like the settings icon. I used to put links to certain settings pages I used frequently (e.g. WiFi settings; page that shows battery stats) on my home screens but stopped because of the ugly icon (I use custom icons now because I still want the shortcuts; don't want widgets).
It frustrates me that despite all the customization we can do with different launchers, themes, widgets, etc. it's extremely difficult to make our phones look particularly nice because the design of everything is so wildly different. There always ends up being one or two things (app icons or widgets) that you want to use that you just can't make look nice.
Personally I do care about function over form, but I really like nice design too, and anyway we're talking about the UI here and the UI ultimately determines how functional things are to the user. Where excellent functionality and pleasing design meet is where I like to be. Hard to find though.
I use a macbook pro as my main computer (coming from linux, which I still use on other computers) and I think the OS X and Mac hardware design paradigms are probably the best in tech these days (does require some customization). However, when it comes to phone design, I don't think Apple got it right with the iPhone - lots of things I don't like there. It's much more consistent than Android, though, you have to give it that.
Finally, I'm glad we can all agree that the glassy, glossy, blingy "eye candy" type design is awful. I much prefer matte (flat-ish) graphics for everything - icons, widgets, UI, etc. Kind of an OS X/Web 2.0 standard which most are pretty good at moving toward these days.