Good points Mike. I believe that research was done by the Illinois Natural History Survey people?
In my state of Indiana lakes are pummled by anglers that keep as many large males as possible as there is no bag limit or size limit. I've seen people wipe out a channel of spawning bluegills in a couple of days.
I guess our state has not seen the research as everytime a regulation is proposed by John Q. Public it's shot down, and the reasoning given is the more bluegills harvested the faster the growth rate due to a better food supply. Overly simplistic and outdated.