I agree that the issue needs to be addressed.. but I don't think your solutions are good solutions.

The reason I think that is because it is well known there is a non-intrusive 3rd party tool provided by guildworks that provides a user defined chat filter. People with the filter have confirmed that they see next to no RMT shouts/tells when properly configured.

SE will not eliminate RMT, it's not possible, otherwise countless other MMORPGs would have already done it. Banning the buyers will only add animosity to the community because a lot of people who buy will complain and claim to be legit. We already saw this happen once at launch when a digit was removed from every bodies gil if they went over a certain threshold. The bottom line is that SE would have to hire a significantly large amount of people to investigate the number of cases that exist and they're not going to do that because money.

Something they can do though is actively monitor RMT shouts/tells and adjust chat filters accordingly. Currently the chat filter they have in place only filters duplicate messages that are sent in high frequency. That's why you see RMT shouts/tells changing a few letters in their repeated advertisements every 2 or 3 messages.

In the end, if a 3rd party, user defined chat filter is able to handle RMT shouts/tells then why can't SE monitor/update their own chat filters to do the exact same thing. Yes, it will require somebody on their end who actually monitors and adjusts the filter but I bet people wouldn't care about RMT that much if they weren't forced to look at shouts/tells from them.