When Manley closed, season ticket holders were told in advance that they were moving to the Dome, and everyone was given the opportunity to select their new seats ... or choose not to renew.
SU can't spring "seperate seat assignments" on season ticket holders after the fact. The renewal deadline was 10 days ago, and no mention was made of being moved to a different / worse location for the Duke game. That's false advertising.
It's usually not a good idea to piss off the wealthy alumni and preferred season ticket holders (the people that write the really large checks every year). While I doubt that anyone will cancel their tickets over this flap, it's not beyond the realm of possibility that angry people will write smaller checks to SU going forward. And contrary to your rather naive opinion, people aren't lined up around the block waiting to make $5000+ annual donations for preferred seats, so it's in SU's best interest not to alienate the current donors.
Are you even a current season ticket holder? Because if you're not part of the group of 10-15,000 people that are affected by a potential move, your opinion is irrelevant.
And the last time I checked, JB and Hop had no problem recruiting 5 star players, even with crowds of "only" 30-35,000"