While I can appreciate the desire and possible usefulness as a tag, I am against it.
First, it can be overly broad. It can be anything from changes in your environment, changes to family dynamics (divorce, marrying into a family, etc.), changes in behavior (my child used to be so well behaved and now they are totally unruly, what changed?), to how to change behavior or probably some other things I can't think of at the moment. I realize that this could be, at least partially, solved by a good tag wiki. But I fully expect users to look at the word "change" and decide it is appropriate without reading the wiki.
Second, the oft-touted wisdom is that tags are so people can find questions in areas that interest them, or things they are experts in. With such a broad definition, being an expert in "change" is kinda hard. It also doesn't lend itself well to finding questions. If you want to look up things about divorce, that tag finds you questions that are probably what you are looking for. I feel like change would be hit and miss.
Third, can it stand as the only tag on a question? Again, I'm going to go with no. If I told you I had a parenting problem related to "moving" you would already have at least some idea of what the problem was about and if you might have any insight or advice. But what about if I have a parenting problem related to "change"? Changing locations? Changes in my daughter related to puberty? Those aren't even close to the same topics.
I feel like if ""change" were something with a narrower definition without so many possible meanings it could work. Also, since it only really serves to describe the other tags on a question, it doesn't work.