This plugin was born out of a very simple need. Back in the day, when the wpautop filter was really sucky, I got annoyed and turned it off for my blog. However, years later, me (but mostly my co-author, Halfgaar) got equally annoyed by having to manually type in all the angle brackets. I wanted to turn on the filter again, but I didn’t want this to affect all my old posts. Hence this plugin. See this blog post for more history.