My two pence worth. They COULD have built some bridges here and just released the 'upgrade' free. Not exactly something bean counters would like but coming from the viewpoint of a user, the problems in the program that have been ignored for so long could have been smoothed over with a bit of confidence inspiring publicity.
I think they missed a seriously good opportunity to start fresh without the prior bad blood being part of the mix, that and a little more information.
Sketchup has good points as well as bad and having looked around I will acknowledge this. Why some problems have survived as long as they have confuses me but, bean counters industry wide STILL have too much influence over the fix bugs or bring in shiny new features arguement. My prime premise still stands, why point out the simplicity of sketchup and then struggle to fit new applications within it? Why when there are basic items that require fixing? The change to the extentions is worthwhile imho, I know that independent ruby scripters kept things rolling for some time but frankly this might be a mechanism for proper control, removing scripts that are not worth the download time and ease stability problems.
If you want me to list all the issues you obviously missed the last few years here at sketchucation, we all know the things that could and should be simply done to improve the program. My two pence worth.