Sometimes I have to grasp a knife with a deep carry clip slightly differently, but in the end I don't have an issue. Also I usually put paracord on my knives if they are like that. For instance my ZT 0562 has a deep carry clip and with a little 1"-2" length of paracord weave on the end it helps you grab the knife and remove it from your pocket.
I think it is sort of a fad and should be optional. For me... It's like if I am going to a place where I can't have anyone see my knife or there will be some kind of bad consequence (work, police in Philly) then I'll put the whole knife in my pocket. Not taking any chances. Deep carry only comes in handy when you kinda-sorta don't want to advertise you have a knife but in the end you don't really care if some joe blow sees it. Cause like I said, if there's consequences of someone finding out about it then the whole damn knife should be pocketed, not clipped.
So basically I don't care, I don't prefer or avoid deep carry clips. I do agree they make knives a little harder to deploy like I said, but I typically find a way around that with paracord or draw/grip adjustments.