My two cents:
You're absolutely right. GGT was banned to weaken, but not completely destroy Dredge. Then, shortly after, they changed their minds and decided that they'd rather just kill Dredge completely, and banned
Dread Return
.
There is absolutely no reason for it to still be banned, because Legacy Dredge cannot port-over into Modern at all without
Dread Return
. However, Dredge is one of the most universally hated decks in existence, and unbanning GGT would be suggesting that they actually
like Dredge, which would not go over well.
Don't hold your breath.