That 3d spotting would have sense if mortars did something, but they can't kill a thing.
Also, not being able to deploy on your base removes the only option to fight back enemy mortars when your team is being pwned.
I'm using it regularly because other gadgets like airburst, are also useless. Wall and defibs or wall and mortar are the best setups for support. Smoke is redundant, airburst 25m range is a joke, specially on conquest or escalation, and the defending ones are usable, but they get destroyed after only 1 activation, so are also pointless.