Logically speaking if a weapon had access to 3.4x and above it wasn't all that rational why it didn't have a 2x too. Some guns like the Rhino desperately needed one as well. For most rattly CQC weapons a 2x is not a very good idea in the first place, so I don't see much harm in it. The TAR won't be better than the TRV at 2x Reflex usage just because it now has one, and it wouldn't have been the case if it had one before.
Long overdue, but I'm still using iron sights until reflex sights work properly and don't put you off target especially while moving.