You seem to have a real problem with avoidance bosses when did one hurt you?
It's that they become really boring really fast for me, but for some reason they've become a fad in modern fangames.
It irks me when something comes down to nothing more than long strings of memorization. Not to mention that the human brain is limited to the amount of information it can take in at a given time, so concentrating on every projectile in an avoidance segment that could potentially be a threat is overwhelming.
What I want to see, and what I grew up with, more or less, are bosses that you have to damage in some fashion, and that when mastered, don't take three whole minutes.
This is also one of the reasons I fell out of love with Guitar Hero. If you fuck up ONE note, you have no chance of 100%-ing the song unless you start over. The songs are several minutes long, so one mistake costs you that much more of your life.
That's basically my perspective. You can disagree if you want. I tend not to give high votes to games in my contest that utilize avoidance bosses, but other judges might enjoy it. It's not out of the question that an avoidance boss game could win my contest one year. I just personally see it as unlikely.