yeah, remember its a "minimalistic bulletin board"
Its been made to be fast, and minimalistic. To include signatures would mean to change quite a few things. Currently it only needs to do one mySQL query to load each page of posts, if you wanted to include signatures or post counts etc you would need to do one query for EVERY post on that page. (it would have to do a query to get each members info)
So to include signatures would take away a fair bit of miniBBs speed advantage. | 
