yea I can see that happening. Part of it can be dealt with with an appropriate excerpt, but I guess many users won't actually read that. It is also true that it would fit many questions.
About "keeping it under control"... to be honest, I'm under the impression that most questions need to be retagged manually anyway (I'm pretty sure I needed to put [tag:programming] on most of the questions that currently have it), so I don't see that as that much of a problem