In principle I agree with you, but for a lot of people this will feel like they're being exploited whether they want to renew or not. Football is far more emotive than most decisions on how to spend that disposable income.
There are a lot of downsides for the year at Wembley, but most ST holders will be kept on the hook because of the excitement of the new stadium. Its the same reason that Wembley were able to get so many people to buy into 10 year seat licenses when it was being redeveloped.
Personally, I've only had a ST for a couple of years, so I'm not particularly attached the people who sit around me. I'm going to take some time to think about it and wait for the second window.
Can't help but think that when nostalgia kicks in, I'll be much happier that I had a seat for the final season at the old ground over the first at the new one.