Mm... Fair point. It just seems like another fundamental change to allow twitter messages to go to >5 people at a time. What would be the limit then? Ten people? A hundred?
Maybe limiting the number of people at all is a bad thing. Who knows.
But messing with their Formula That Works may be a bad thing.
Going from blog posts and mailing lists to 140 character messages was a real change in communication. Going from 140 characters to 110, because a couple of people have long twitter IDs, is just being a pain in the ass. I already compressed the point of my message to 140 characters, why isn't that good enough?