I think the way to think about this is that A) they haven't really gotten rid of the 10.5 ipad yet, it's SAME price as yesterday. B) this is a BETTER ipad than that so it's 150$ more than the 10.5" ipad. C) +cellular is 150$ more than wifi, historically it was only 130$ more, so with the new radios (which includes wireless charing for the pencil) it's 20$ more than last years upgrade to wifi+cellular.
i think the screen, edge to edge, speed, thin-ness, usb-c charging port (faster charging), wireless pencil charging, faceid, are probably worth 150$ more than last years 10.5 model (Which was basically a 2nd gen chassis)