Not saying that the brains are literally left out in the sun for 20 minutes, just that it would be like filling the brain with microscopic blenders (bacteria). Even though it might not appear any different on the outside, the consciousness once housed within would be completely destroyed beyond repair.
As to possibly being able to recover a busted brain the same way we recover a wiped hard drive.. I know you addressed this taulover, but it really is a bad analogy.. Recovering a hard drive is like reading a book where random letters have been erased or altered. Recovering a damaged brain is more like putting two halves of a cut fruit back together. You could make it look like it had never been cut, but the connections between the cells will still be severed..
And cryonics attempts to reduce the damage as much as possible, with a process that involves things from CPR-type techniques for keeping blood flow to the brain to the ultimate vitrification process, so that the people of the future have the greatest possibility of reviving the person. It would certainly be many orders of magnitude easier than if your brain were rotting in the ground.
Anyway, I'm not saying it's completely impossible, just impossible with current technology. I wouldn't recommend cryogenics cryonics to anyone, it costs a literal fortune, and you could spend that on making people who are still alive less abjectly miserable instead of trying to selfishly project your consciousness into the distant future. I think it's evil.
Calling cryonics cryogenics makes both cryonicists and cryogenicists unhappy. The two are about the same as geography and geology (or if you prefer to consider cryonics silly, astronomy and astrology).
It also is not that obscenely expensive; Cryonics Institute charges $28,000 for its service. So about three or four times the average cost of a funeral. Or about as much as some upper middle class people spend in a single vacation. Under a life insurance policy, this comes up to several hundred dollars a year. And considering that many people spend similar amounts on other selfish things (food, Netflix, video games, drugs, etc.) rather than donating to charity, I really don't see how it's any less evil than normal people things that normal people do. Of course, if you're living an ascetic life of charity, or if your cryonics decision is motivated largely by charity, that changes things, but otherwise, I just don't find that a compelling argument against cryonics.
There is also
the argument (though I currently don't think I agree with it) that cryonics can, assuming a small but non-zero probability that it works, probabilistically save lives if given widespread adoption, and as such supporting it may be a good form of charity.
(Edit: And I'm assuming you didn't read the Wait But Why article I linked initially, since you seem to be repeating points that the article argues against, rather than arguing against those counterarguments?)