What many are looking for is an interface which looks more like what you would find in a "a real life" recording studio.
I think it mainly centers around the design of the Radio buttons (which can be hidden)

I'm sure when they were designed it was with the thought they would be recognizable across wide geographical areas with different language backgrounds.
I think critics may want something little more "clinical" and a little less "cartoony"?

Probably along the lines of the layouts for Sonar:
http://www.cakewalk.com/products/SONAR/X1-Studio/

Or Reaper:
http://www.reaper.fm/

or Ableton:
http://www.ableton.com/live?a=what_is

These do look a bit more like an Excell spreadsheet
RealBand is closer to these than BIAB in appearance and getting closer.

My guess is that a simple redesign of the radio buttons would probably appease most critics though as an illustrator I do feel they do have a certain funky charm.

As I have mentioned in another post, give the user the option of a BIAB "Modern" GUI or a BIAB Classic GUI and most would be happy....or not?

Can't please'm all.

Have a good one,
Carkins