So tall guys are ok if you put a TE label on them but not a WR label? This is part of the slight bias against ISU. It's more of a favorable bias towards Iowa TE just because they have had 2 or 3 guys have some success. That really has nothing to do with these two but it is a bias.
Hockenson and Fant are 6'4 and 6'5 and 250 lbs. Pretty average sized TEs. But they are fast and are good route runners. They still have to block DEs and LBs, so odds are that capability is going to come with a bigger frame. In general the trend of quickness and route running over size at the TE position has happened as well, it's just not quite as massive.
I think anti-ISU bias paranoia is pretty silly. If there were a bunch of guys in the league outplaying their draft position from ISU you might have a case. ISU guys don't get drafted because until this year guys weren't good enough or aren't what teams are looking for. Tons of guys are getting into camps, so it's not like ISU guys are getting black-balled or something. Iowa TEs get drafted because they're good on film, they show up at the combine and perform well, and happen to be in the mold of what NFL teams want right now.