Positive
Lockdown prevents long, one sided games where for some reason, the defending team is totally superior to the attacking. I've had games like that many times in RO and it was often not fun. They happen here too, but the lockdown tends to put a merciful end to the situation. And the mad rush for objectives may actually turn a bad situation around for a losing team. It also promotes the 'kill to death ratio' types to get into the objectives at hand, instead of just killing the other side.
Negative
However, it is true that lockdown with the current time limit, removes the option of winning by killing in some cases. And it also causes the 'mad rush for objectives' as the timer runs out.
What then?
Auto-balancing teams could get some attention, spawn points overhauled a bit, squad communications (important more for the attacking team) improved. And if that fails, slightly increase the lockdown time. No biggie.