This is a move in the wrong direction. If anything, the title and tags fields should come after the post body.
I find that many users, myself included, occasionally write tags and titles that don't fit their questions well. There are many possible reasons for this, including
- OP focused on a minor or irrelevant aspect of the situation due to naivete/ignorance,
- OP rubberducked part of the problem out while writing,
- and the classic OP just doesn't know what the icosahedrons he's talking about.
Back in school, I was taught to write titles for essays last. That way, they would match what I actually wrote, rather than what I initially thought about writing. For similar reasons, newspaper headlines are generally written by editors towards the middle or end of "layout time," not by reporters at "write time."
I've already stopped following the layout of the ask page when I ask questions. I write the body first, then enter tags, and save the title for last. Doing this has improved the quality of what I post and the responses I get (in my opinion, of course).
The obvious flaw here is that people could waste time writing duplicates that would have been found by the similar title search. However, the title search does no good if it's searching on a bad title. I would like to see numbers on how often that feature actually works, although I have no idea how to collect such data.