If [someone] wanted to, they could fill these block up over night [by spending a lot of money on fees]. Either that, or you could get enough demand that would fill it up very quickly [which is both what we want and why we need it]. You will end up asking for X MB afterwards, which would further centralized Bitcoin whilst not improving [efficiency].
Using terms like "malicious attacker" doesn't convey any useful information, it's an attempt to make people feel a certain way about the topic being discussed. And that is what makes you a sophist. Anyone has the right to send any amount of transactions they want for any reason or no reason, that's one of the main points about bitcoin. No middlemen regulating what is allowed.
We need more throughput. Otherwise this is as big as bitcoin is going to get. Squabbling over how it should be done instead of actually doing it is hurting everyone.