Some of it is folks who feel repeatedly burned by DC and don't trust them ever to get it right at this point.
Some of it is vindictive wishful thinking by those who were attached to the DCEU and resent its getting round-filed.
Being in neither camp, I'm excited to see what Gunn and Safran come up with.
There might be a couple of nuances in between but overall I think you've nailed it.
Personally I'm Camp #1 with maybe a slight hint of Camp #2 because of the way they(whoever 'they' are) treated Cavill.
I'm not sure I'm in Camp #3(excited to see what will develop) but I am curious and open. Camp #4?