a) is it a good idea?
Yes, it is :) As I see, at least Serbian (we want that), Croatian (one contributor is strongly pro, one realizes that it is correct, one is against), Serbo-Croatian (I am a "linguist consultant" there ;) ) and Italian. (As well as I can say that Bosnian Wikipedia should change it, but people from bs: should be asked.)
The problem is that a lot of the "first contributors" on small Wikipedias don't know their own orthography well. (For example, until we realized that admins can change MediaWiki interface 0:) we had interface translation on Wikipedia with a lot of orthography errors.) A lot of them are the first just because they use Internet, not because they have correct knowledge of their own orthography.
This means that should be general MediaWiki policy and it should not be used only on Wikipedias where communities are strongly against it. So, Names.php should be with small letters in the main distribution, but it should be changed for Wikipedias where communities are strongly against.
b) is someone prepared to do the research, change all the necessary entries in languages/Names.php, make a patch and submit it to bugzilla?
If other people think that it is OK, I can try to do that (or to help to someone to do).