Yes, that's a good point.
It depends what fields has every forum that needs to force users.
If you put them all at once maybe it will happen as you say.
I don't think that there will be so many fields to use this modification. But it will be much help when ever we make a new field. You know what will happen. Mod will force users with the standard post count. Many fields that I have seen are different regardless of the type of forum.
We may force them to put there "Real name" after 1 post, but we cannot force them to write in which forum are fun, after three months (this field I had experience before 6 months on a Site that I was register.
Any way this could be an + option and all other exists to.
Lets see here other users what to say. And finaly as it is, is very good