Sounds good... right up to the point when there's a problem. Then what happens? systemd notices that the log is corrupt, and... deletes it. No log of the problem. See: the long and angry (and unfixed) bugzilla tickets.
As for log compression, you don't want the actively written log to be compressed. If there's a problem, even as small as a single bit error, then the log will be unrecoverable. That's the tradeoff you make with compression. logrotate compromises by only compressing older logfiles. If there are any minor errors in the active log then you can still read it just fine.
As for tampering. It's of minor importance only. While the systemd people and their fanbois might harp on about it, they are catering for a problem which is of far less importance than hardware failure or power loss. Right now, all that foward hashing is so useless. If a simple power failure causes the checks to fail and the whole log to be discarded, it's a net negative. You threw away all my bloody logs! Like many of the systemd features, there's a whole fanfare about how essential it is and how everything else is awful and insecure. And as usual, there's some small credence to the claims. But it's massively overblown, and it has significant downsides. The "scary" things you mention are all of low likelihood--they only apply if your system has been compromised; there are rather more likely and less nefarious things to care about before these. I'd rather have a guarantee that my logs won't be deleted on a whim. Never, ever delete my logs!