1. A little big, at least, bigger than Schoeps or DPA 402x
2. It's not the "full spec" design of the DPA 40xx series but a simplified design to reduce cost.
3. They're still expensive -- you can have brand new AKG, Milab(?), MBHO, Audio Technica, etc. that are probably just as good for the same or less money.
Not trying to go out of my way to knock them -- I think DPA makes great products and I loved my 4021s -- but I think this is why you don't see more of these. For that matter, with some careful purchasing decisions, $1800 will get you a Schoeps active set. Others call DPAs "dry" and that is probably fair; it's certainly my experience that (a) they sound great in ideal conditions, (b) they sound less great in not-ideal conditions, whereas Schoeps seem a little better at recording PA systems regardless of location. My $0.02.