I thinking they're more or less looking for a simple solution, removing tags from two thousand or so items is going to be pain enough, but to ask for custom coding to make the items attuneable as well, I think would take forever. Easier just to drop the tags and be done with it so we can kick start what would be a buzzing economy.
Now if we really wanted to do attuneable items, I think it would be a good idea to draw the line at ToV set armor pieces that drop from trash. That way we get a large majority of the lower end items taken care of in one fell swoop of tag removal, while the coding that would take a bit longer is limited to a single set of armor.
This would speed the process, and simplify the work that the devs have to do in the long run.