Or, you can RMT and buy runs through things to get the gear too (you get tomes for those runs -plus- whatever items). Seriously, using RMT as an excuse doesn't work. You can mind-numblingly run dungeons with little to no effort to get soldiery gear too (I assure you the dungeons aren't really going to take effort and wipes and work once they've been out for a while). Horizontal progression doesn't destroy the game. At all. RMTers might, but that hardly has to do with crafting and items.
Having the equivalent of myth now is basically the same as having the equivalent of Philo.. it's useless. Crafting (for the very large part) in this game is useless. Heck, even the high end foods for culinary (the 2-star stuff) is currently useless. I also, just for the record, don't think ANY tome gear should be BiS. People like you don't seem to have a problem with that though. It's fine to put very little effort into getting tomes and get a BiS item, but when someone puts effort into earning gil to legitimately buy an item they somehow don't deserve it (and shame on the crafter for selling it!). There are MMOs that have crafting with gear that is very near to BiS.. and those games aren't broken or destroyed by that gear.
You're the one throwing around some scenario where people have to buy the stuff, or pretending RMTers don't already get gear for gil as is (even though the Coil, HM, and EX runs I've seen being sold beg to differ). The case you're trying to make, doesn't work. Having multiple gear choices is good.
I want more gear choices. I don't actually make money on the market. If you were to look at my crafting sets, they aren't melded... heck most of them aren't even all HQ. I leveled crafting to help people with gear for alts they were leveling. Now that everyone is done with that, my crafter side has been resigned to making food for raids. Getting materia up to craft 2-star gear for guildies just isn't worth it when they can easily get full DL in a week and be on to myth. The same is going to be true for the myth equivalent stuff. Having done Coil (with the exception of Turn 5), and having nearly BiS gear on my PLD (I'm missing 3 pieces from the list) I can say that getting dark light is FAR easier and requires way less work and attention than maxing out stats for materia on my gear (and who knows how much that would cost, or what the new needed stats would be).. heck, even getting myth pieces is far easier than the work I would need to put in to have the ability to craft stuff that's only marginally better (and only when penta-melded) than Darklight.
I want choices, I want stuff to be useful and not just sit there. I'm not actually out to make money. I would actually call all the folks who want tome gear to be BiS the lazy ones.