They, by heir own Blog, are the largest 3rd party developer (now that eBay has closed itself to new developers they will remain the largest no doubt) on eBay. That said there is no excuse for a firm of this magnitude to not respond when asked can the new layouts be returned. As others have said short sighted, near sighted, or no sighted but definitely not far sighted.
If they had taken what they already had (instead of taking things away as seems to be their wont) and built on it they would have had a new feature, that they could market, that accommodated those that wanted the Mobil-centric layouts and those they were more than happy with what they had. The change probably could have been done just as quickly and cheaply if not more so.
How:
1.. add a check box to someplace (Auctiva should be more than capable of knowing where it their system that makes the most sense and is the easiest to accomplish) that has one task. That is to either show only Mobile-blessed layouts or show all layouts.
2.. once the checkbox is checked look at it and if it says I want only Mobile-layouts than show them only mobile layouts.
3.. if the check box is not checked than show all the layouts.
end of change