Depends whether it is a lift to the body or the suspension
Assuming suspension, the standard trailing arm will be now putting stress on the bush where it attaches to the chassis because it is now at a different angle to standard. Cranked trailing arms neutralise this angle change so the bush will last longer.
Cranked trailing arms are usually a bit longer than standard so also help with axle articulation.
Do you need them? If you are not doing much offroad, probably no. Are they good to have ifyou can afford them?.......I think so.