I can't say how popular this would be, as I just don't know, but I would personally appreciate an increase to the Blacklist capacity.
Now-a-days there are *so* many Shoutvertisers for FCs, or some Random Club there's already 15 PF advertisements for, and they're all very disruptive- I'd like to Blacklist them.
There are also plenty of people in PF who simply aren't conducive to cooperating, or learning- I'd like to Blacklist them.
And on top of that, there are people who are just rude, disrespectful, or just straight up antagonistic- I'd like to Blacklist them.
The issue is there's not enough room for all of these people, especially now that NA has Four Entire DCs full of people, 200 simply isn't enough to cover all these.

I have no idea if this is a widely desired thing, or if this is even a do-able thing, but you miss 100% of the shots you don't take. I am bad with words.