Creating new tags is a "Bad Thing"™
The purpose of tags is two-fold. One part (the lesser part) is, as you say, to make it easier to find similar questions. They accomplish this by sorting tags into narrow, well-defined categories. Sorting into categories only works if users all sort into the same set of categories as other users. Thus, creating new tags should be something done with care, because a new tag by definition is not used by anyone else. There are now more than 50,000 tags on Stack Overflow. If you can't find an existing that works, perhaps you're not looking hard enough.
The other, more important, purpose of tags is to connect your question to an audience of qualified answerers. This works because these answerers can mark specific tags as interesting or subscribe to the rss feed for that tag, and mark other tags as ignored to reduce the clutter and noise. If you create a new tag, it's guaranteed not to show up on anyone's list of tags they follow, and is therefore a waste of one of your five allowed tags.
Remember: the purpose of tags is specifically not to summarize or index your question, but rather to categorize it, and that is a subtly different thing.
Finally, you claim this change was made without announcement. Perhaps you should pay a little more attention here to meta (specifically, this question), where this kind of change is not only simply announced, but discussed first so you have the opportunity to have feedback. There have been times where management proposed changes that were never implemented because the community here said, "No."
