Yea, ego is the the reason for the demise of "main_block".
Actually it isn't, but you just keep going, since you seem to be on a roll.

ETA: To address the other points..........
Hey you get to moan more than everyone else. This time it is my turn:
- Why are you changing the "main_block.png" to "bars.png" and moving all the graphics around so that it is a time consuming PITA to guess at the format and make a new one?
- What's with all the "smalltext" in displaytemplate.php?
- I am sure there is more...

1/ Because the image no longer has any point in its 2.0 form. The structure of the theme has been simplified by removing all of the spans that took up a large part of the old main_block image. The header and footer of the theme no longer need the massive chunks of graphics that made up more large parts of the old image. The rounded corners are all done with CSS3 now. Etc.
Bascially, there is no point in having the old image any more. Since a lot of people apparently found the old image confusing, both in terms of css and in terms of editing the actual image, getting rid of it is perhaps not a total disaster. Getting rid of it will also slightly reduce bandwidth usage, since the new images are a lot lighter. The number of http requests for images is not increased over 2.0, so cache times should still be good.
IF you are concerned about the actual
name of the image being changed, I cannot really see why this would be problematic. However, if enough people think it is problematic then the image can be called anything at all.
2/ It's a leftover from 2.0.x. I assume you think it is equally disastrous in 2.0.x. You may be pleased to know that, since this is an alpha build, things are likely to be cleaned up a bit before the final build.
3/ It's alpha, and it still contains unnecessary leftovers from 2.0.x so yes, there is bound to be more. I already have a personal hit list of "more".