The thing about an unused season ticket is a red herring. You buy a season ticket and it means you've bought a seat for the season, just like someone shelling out for a box for the season, it is yours, if you don't use it a particular week then you're entitled to let other people use it on your behalf.
That's not the same as paying student prices when you're not a student, but I think the club probably make more than they lose through people using the 'Tyrant Money Saver Policy'.
Personally, I'll probably pay full whack for home games, scam student tickets for whatever away games I can and happily make use of any unused season ticket But I would definately go to more games than I do if full prices weren't so high.