I'd think it's more OT figures who had Vinty figures that they'd really rather save for a return to the vinty cards... Doesn't mean there aren't a plethora of other OT figures they couldn't or wouldn't do... Just modern Lobot NOT being on a vinty card does make sense, as does Yakface, etc.
I'm a little surprised Biggs isn't being held back, actually. Only because there's certain guys who were never in the vintage line that you raelly WANT that card for them... Tarkin, Fleet Trooper, etc. Biggs would be on my short list of those characters. I'd also put Owen/Beru, Imp Technician, Chief Bast, Nik Sant, some of the Cantina aliens (many that could stand an upgrade), etc.