The quality of the parts do mean something . better made mean better build and will last longer. I think one of the problems you are having is the bolts or nuts holding the cranks onto the BB axle keep coming lose and in turn the crankarms are losing from the axle as you are riding and are getting destroy . One way around this is to use a treadlock on the bolts or nuts . use the blue one, that way the cranks and BB can still be service when needed.