I consider of having lockout as essential - but after several months on fully bikes I use it less often. Use it always on road and on some steep climbs. At the moment I don't use it on flat climbs (but I used to). the extra "comfort+control" you get offset some bob
In my superlight (one bar, 10cm travell) there is some bob even when you pedal in circles. When buying the frame I ordered the lockout (which costs extra
). Funny thing but on the road, superlight when locked feels some kind of odd. Once you block it you feel that now your full body bobs.
So can you live without the lockout? Yes, but you will feel annoyed while peadaling steep climbs and your energy goes into bob. (especially after you switch your hardtail for fully)
The extra money for lockout can be $50 - but in my opinion its worth to pay extra