No miners would voluntarily run a system that does this. They may get higher fees, sure, but they make the system vulnerable to double spends by accepting later transactions to different destination addresses with higher fees. By making the entire Bitcoin network vulnerable to double spends, they ensure that the higher fees they get are worth nothing.
If you ask me, the reason - in part - that Bitcoin has been successful so far is that there are monetary incentives to keep the system running by the rules. If we start to depend on miners "doing the right thing" because we assume that they are concerned with the long-term survival of Bitcoin, I'm not sure things will continue to go well. Looking at the average human, it's hard for me to see that we are all that concerned with the long-term sustainability of important things that we depend on. I don't think miners (being human beings) would be either.
This is an interesting discussion though. The 0-confirmation double spend problem would definitely be a valuable one to solve. I do think it would have to involve some form of centralization though. Not that this is necessarily a bad thing though, since no one would be forced to go this route.