Depends. If you only have a single suction line and a single return line, it would be better to at least have the suction line be 2". If you have 2 suction lines (skimmer and floor) back to the equipment, then having both be 1.5" would likely be fine.
It can certainly lower the head loss and increase flow rate by using larger pipe on the pad where at the twists and turns happen.
It really should not be that much of a price difference to use the larger pipe.
BTW, my pool built in the 70s only had a single 1.5" suction line and a single 1.5" return line and it worked fine even with a large pump.