2. This concern is legitimate. There are going to be people that do not have good quality of life, or even a good brain, after being brought back from cryonics. It's a price.
3. You're arguing for the status Q, not because it's the best, but because it's all we've ever known.
I think everyone who is cryonically frozen is ready to be shocked by the future. They understand moral relativity and how it varies with cultures, and they're ready to see what cool stuff our descendants will come up! After centuries of being frozen, I think that it will be legitimately interesting to meet someone from our age, and we may still be able to find a place in that world. I also think that we should be looking at what's best for the individual being frozen, not what's best for a hypothetical culture in the future. If I am reawakened in the far-flung future, I don't have any grand plans of reverting their culture.
4. I met a former employee of Alcor at a conference. She was also signed up with Alcor, and was currently working on cryonically freezing other tissues. She knew her shit, wasn't just locked into cultish thinking, and believed that there is a decent chance of some cryonically frozen people coming back.