Well I don't know why they don't have some way to jump to a season or remove a season I've already watched. I don't know why you can't use Page Up and Page down. It seems they are only thinking of people using a web browser, not a remote control. They have plenty of examples of good interfaces for HTPC: xbmc, Boxee, MediaStream, PlayOn, etc.
Oh well, I'll just use my browser.