If this is true (I have no reason to think it isn't), it stinks that all of us multiboxers are just suffering from an unintended consequence from a completely unrelated bug fix.

I am happily dual-boxing, as I am quite used to driving a couple of teams in WoW at the same time (duoing transmog runs or even heroics is much more efficient for two teams at once and something I've been doing for a long time). I simply keyboard run one team with my left hand while mouse running the other team with my left, then attack with my left and it passes to both. Works the same for two toons in SWTOR. However, I'm pretty sure I'd be 3 or 4-boxing SWTOR if follow wasn't an issue.

On a bright note, one place I've found in SWTOR where multiboxing works absolutely perfectly: Ship Combat missions! It is great to get my toons on their ships, then turn on mouse broadcasting to select navigation, click on a combat mission, and blow stuff up X2 (and get both toons all the XP and credits at the same time). I make sure and do those every day.