Only people that post on the Forums have their Display Name visible to others currently. Even then we took that into account when designing the updated system and I wouldn't recommend trying to attack known Display Names...
So two things here. Not everybody knows your Display Name, and an attacker will need to figure out your email account in order to attempt to take over your SWTOR account. We are implementing a few other measures (more news on that in the few weeks!) to ensure that account take over risk is mitigated.
We did look at using a secondary 'login only' display name, but sadly this would create more confusion and increase costs associated with support of the new system rather than decrease existing support costs. And again, I stress that knowledge of the Display Name in of itself is not a security measure - we have many other controls in place to mitigate that knowledge.
So apparently people willing to post on the forums to give feedback are not considered important enough to protect properly because it would cost too much.
I STRONGLY urge you to look again at a secondary login name.