1) You could limit the transaction size while still increasing the blocksize.
It's not a matter of 'could' or 'could not', but rather a matter of "should" or "should not". I disagree with those limitations.
2) ETH did fine.
We're talking about Bitcoin, not a mutable shitcoin.
3) Few shops actually directly accept bitcoin without an intermediary. Those intermediaries should be bitcoin-savvy enough to prevent damage to the merchants. Those merchants that do accept bitcoin directly probably know enough about it as well.
This argument has no relevance to what I said. You don't know how long it takes for those "intermediaries" to upgrade and test their custom implementations (hint: 28 days is ridiculous).
4 & 5) The increased costs is only marginal.
A minimum of 2x increase is "marginal"?
And most people have plenty of room on their hard disks..
You can't know this. Example: I have to upgrade my node soon due to inadequate amount of storage on it.
Oh, and I forgot to mention that in case something goes wrong with your datadir (if you use Core as a wallet for example), you will spend a ridiculous amount of time fixing it with absurd block size proposals.