If anything, we should be banning miners who refuse to do reasonable filtering like this.
Banning is such a strong word, though. If a majority of miners would in fact refuse such transactions other smaller miners would start getting a lot of orphans and would be forced to either reduce their blocksize drastically or starts filtering out what goes in to their mined blocks. But that's only if the majority of miners sees that as a good thing for the network and their bottom line, no?
If miners refuse to do their job in filtering, there's no reason to leave it up to miners.
Regular participating nodes can refuse to relay blocks with (eg) more than 50% Dice spam.
Even better! So the people that in theory are the ones losing out from all this have the power to do something about it!
A new kind of poll is born, a client that does filtered relaying where the user can opt as to what kind of filtering to apply gives that user a vote. Then it is not just he said, she said, it's actually measuring user opinion.
But having clients decide on their own relay rules opens a whole new can of worms, of course, and will ultimately open a new angle of attack against bitcoin stability. It does present an interesting case, perhaps worth discussing further.