The problem with the "earned it" philosophy is that other activities such as Nightfalls are not remotely challenging. The people who look down on "xurners" are the first to bitch when there is no burn on a Nightfall, it takes more than ten minutes to complete, and doesn't give them exactly what they want. Access through Xur is balanced in the context of trivial Nightfalls, gorgon chests, and cheeseball raids such as Crota's End.