Because the utxo growth only reduces in a post 110 world if you assume spammers don’t use p2sh to continue their trade or that a state actor doesn’t step in to purposefully spam the chain. The fact is spammers keep block space in demand. Monetary users don’t, which leaves us vulnerable to a utxo attack that could happen so quickly all pleb nodes become useless
So, to be clear you're saying it's bad that they make invalid arbitrary sig data so they can never spend their coins?
Are Satoshi's coins sitting in over 22,000 different addresses bad? You have to keep those in the UTXO set too.