how is it a design flaw? you want one of the best pieces of gear for a particular slot, prepare to pay for it. assume the money is gone. nearly every other modern MMO works this way. once you get something better, keep the old piece for nostalgia, for situational use, or for comparison. or get rid of it if you want. it's not the crafter's problem and it's not the game's problem.
do you get to go out and buy a $10,000 smart TV big enough for an entire wall, use it for a year then sell it at the same price you bought it for or more? how about a car? and what about cheap items like socks? the value of commercial items depreciates as soon as you open or use it. FFXI and FFXIV are pretty much the only MMOs with economies which fly in the face of this, and it discourages crafting quite a lot.
if someone buys a couple rings to test out and they bind after a fight, no problem. get SB to 100%, convert to materia and get some of your money back. maybe even turn a profit. but since when in MMOs with functional economies (read: NOT FFXI or XIV) have you been allowed to buy some of the best, most expensive gear in the game only to just resell it without a loss? if you've played any other games, you should automatically expect to be stuck with that purchase. this also makes money more desirable as it isn't just and endlessly replenishing resource as long as you keep whatever you buy with it.
this forces you to make wiser big-ticket investments, which is realistic- and considering leveling will be heavily quest based in ARR anyway... in addition to gear, money is a common reward for that kind of system. so then what happens if you give players ways to introduce more and more money into the economy along with more and more gear? we had that in 1.0 before materia, and materia didn't heal the economy. it only temporarily stemmed the bleeding.
so now in 2.0 we see the potential for more bleeding than materia alone can handle, and a binding system solves that. and yet people are arguing against it simply because they don't like it and want to have free-reign to spend their cash with abandon, without consequence, regardless of the negative impact on the economy.
who can keep a straight face and argue they care about economic health in ARR and still argue against item binding, especially without a reasonable solution to counter?