I don't see any problem with having an item buy-back option. We have it on retainers and some vendors so why not on the Tome Gear vendors too? Those long lists of gear can get very confusing.
It would be very helpful to anyone with sight issues or dyslexia (one of the main reasons given when it was requested before) and if you're someone who never makes a mistake, it won't impact you.

As to the argument that the present system teaches you to be more careful, I'm not convinced it does, but I don't think game-systems should be designed to teach you 'valuable life-lessons' anyway. I find life quite capable of handing those out on a fairly regular basis, so I feel no need to get them from the game as well.
I play games for escapism and anything that makes playing easier and more fun without having a negative impact on other players, deserves to be considered.