Not going to happen. They don't want people to be able to continually re-use Cartel Market armor without having to buy an additional set.
They can already do this through collections.
IMO, requests such as this are motivated by the desire to avoid credit costs to transfer mods, or the desire to avoid having to put forth some effort. Neither of those is sufficient reason, IMO, to implement something like a BOL token.
To the best of my knowledge, BOP pieces are either drops from FP's/OPS or purchased from vendors and NOT rare world drops. This means that any character has the same chance to get a specific piece of gear. I know it is far easier for a player to run an FP/OPS with their over geared main than with their average or under geared alt.
Using current legacy gear, the mods in any BOP piece can be sent to alts. All it requires is a compatible piece of legacy gear for the mods you wish to send, and some credits.
If you want a specific piece of gear for "looks" for your bounty hunter, for example, you simply need to run that particular FP or OPS with that character. If that means going through the gearing process for that character first, then so be it.
That said, a "token" to make any piece of gear moddable would provide additional appearance options for people. There are many unique looking pieces of gear which are only available as green/blue items and are not moddable and have no moddable equivalent look. I do not think that a "moddable" token should change the binding status, or make gear adaptive, though.
So just make gear that drops in FP and OPS unable to be Legacy bound.