In my opinion (no survey carried out) they look awful and are for people that cannot reliably set up their shifting (another opinion). I have never had a chain drop down between the cassette and the spokes, NEVER!
You do not need to remove the cassette to remove your dork disk, I use a pair of scissors and a pair of pliers. I learned how to do that before I had the tools to remove the cassette (or even knew that you even could do that!) I can't remember that last bike I had that came with a dork disk. Maybe it's an American safety-led thing, like bells and front & rear reflectors are in the UK? (I once auctioned a bell and the reflectors on eBay and got £1.98 delivered - that's how cheap they are!
I do however accept as a good reason to leave it on; that of pissing off people like me!
PS: I have
never viewed riders with dork discs as losers, just mechanically incompetent.
PPS: I have just remembered the last bike I bought that came with a dork disc, it was a bike I bought for one of my grandkids, who was about 7 at the time, she is now 13.