I don’t think we are going to agree on your first point so let’s agree to disagree.
The issue with the garbage can analogy is that the garbage can is 4x more expensive. There is no economic incentive for spammers to use op_return. However, it still allows bad actors to relay illicit data through an officially supported method. Even if everyone still uses inscriptions, this change still widens the attack surface.
The issue with pruned nodes is that if I ran a pruned node I can’t run a transaction indexer such as an electrum indexer which is important for running an electrum server. Without this it makes it very hard to connect my sparrow wallet to my node. If 99% of people run pruned nodes then anyone doing an IBD would have to get the blockchain data from the 1%.