what do you mean by 'degraded manner' for the network as a whole?
other than a lower availability of these spam transactions in any given set of nodes' mempool, it makes little no difference for a node that is enforcing existing policy which is the network at large. it would only be degraded for the participants that want higher availability of arbitrary data prior to the spam transaction getting mined which is even a smaller set of people than the people who actibely upgrade software and/or apply patches.
the argument i see being made is that fee estimation could be messed up, but the thing is that fees are up to the node. their ability to calculate fees on their own criterion of what to bid against is none of anyone's business and certainly doesnt degrade the rest of the network. the node knows whats best, assumptions on what a miner "might" include in blocks dont need to (and shouldn't) be forced upon them.