Generally you don't want to break anything on the svn. When PeriodicTable-3.0 got removed from trunk I went and switched all the addons still using it to use the version on tags. Although even I break that rule at times like I did earlier today when I deleted LibBabble-Tradeskill-3.0 and didn't fix AtlasLoot since I knew one of the devs would fix it soon enough.
I didn't post this because of the removal of BabbleTradeskill 3.0, but because of its creation.
Is there any mechanism in which we can send a message to authors using outdated libraries and ask them to update?
What I did with regards to BabbleTradeSkill-2.2 was just make an update to it (Legitimate :P) and then check out files.wowace.com/errors.txt and see which new zips were built. I updated one of them and sent off a few messages to other authors who use it asking to convert to GetSpellInfo.
I converted ARL to not use Babble Tradeskill, and Mendeleev as well. There's only a couple mods that still use it... most of the authors didn't reply. One gave me shit when I made the quick changes to it as well.
I've been doing this for some addons, where there exists a LibStub'd version of the library, with almost identical interface:
Babble-2.2 -> Babble-3.0
SinkLib -> LibSink-2.0
CrayonLib -> LibCrayon-3.0
SharedMediaLib-1.0 -> LibSharedMedia-3.0