The market was saturated because people already had their equipment trascended, raising arts requires pages as well and doing it on multiple chars has prohibitive costs, and few equips required BGs.
Now we have new equips to trascend, arts will go up to 30 levels, a lot of different new armors requiring them. Indeed, as you mention on your list, a ton of them will be needed.
And yet we have no good source for them.
If the issue was people funneling those BGs, they could just have made them untradable. Removing them altogether is just a fancy excuse to force people to do Goddess’ Grace, as that’s the only decent source left.