So changing primary back would require you to reset again in you didn't like the new primary choice? Ouch.
I wouldn't want to take my character back to level 1 for a third time if i realised changing primary was a mistake.
I agree with the "general idea" of changing primary but i think the idea here needs a little tweaking.
I wouldn't mind changing primary but keeping the level 20 status and then having basic new primary skills and all the secondary skills that have been obtained.
Using just secondary skills in a grown-up world appeals to me more than being a total noob again.