This is a tiny bit off the topic of what the OP is asking. However, I'd like to see SE fix the blacklist altogether. It rather annoying when I've got normal people on blacklist and every time I go into a dungeon I find that hey, I can see what them people are saying in FC. There a reason I put them on blist - so I don't see them talking at all. I don't know if anyone else has ever noticed this, but I'd really like SE to fix this some how.

As for what the OP is asking - there no reason for an increase. Every few months I go through the blist working from the top and clear out about 20 or so RMT names. I try and keep my blist at 100.