Well, I see its uses by plugins that may for some reason, need to connect to a database immediately that isn't in databases.cfg.
I'm telling you, an API shouldn't limit developers like that. It really is a pain in the ass to have to code around such obstructions that shouldn't be there. In the end most of SourceMod's users don't even want to have to touch such files. KeyValues is not a user-friendly format. By building these rather complex functions and limiting developers from at least having the option will be a problem in the future for future developments for SourceMod.
I learned long ago that you need flexibility in a program or you might as well have not even made the damn thing. Right now SourceMod is flexible, but if you continue to force people to use your ways then it will cause issues down the road, maybe to the point that developers start to abandon SourceMod. I mean I do understand why you would want to standardize stuff for the ease of the user but by removing the function to attempt to get your point across isn't a good idea. And like I said before, KeyValues is NOT user-friendly. SourceMod itself is not really user-friendly. That's why there are still people today that like Mani over SourceMod. Mani is user-friendly, and they can understand it.