Yeah I noticed that a lot of people do that now, but I never have yet...
Could I have picked up more by doing it? Probably.
When they implemented letting us see the number of followers, I was blown a way to have 50, because I knew of about 5. Now, I gain 100 some weeks, which is crazy, and another 13 or so overnight.
I think that you are right though, if you remind people that they can follow you, more will probably choose to click "follow" right then.