Don't think it be fair to compare the Hummer with Singapore LSV.
Every weapon is design for a purpose, which it is good at.
Look LSV = light strike vehicle. , while hummer is more of a
general purpose Jeep, the purpose is different.
For LSV, the role is "strike" that is to, go in, over rough
terrains, search and hit the enemy, so the need is for something
light, open so that people inside can shoot freely all around at
things without obstruction. Like the SAS have shown, with their
open landrover, they can conduct lighting strike on air-field or
other targets by driving through shooting up everything, with
machine guns, rifles, genardes. With a covered vehicle, that is not
achieved, therefore you will see all over the world LSV is all
open, due to long proven
experience. You don't want something big, heavy and totally covered
like the hummer, which you cannot freely shoot at people.