They do it to segment their customers. A lot of us startups do it too when we offer one plan for $9 per month, another for $19 per month. The delta isn't necessarily because our costs are different, but rather because the value to the consumer is different.

You could argue that cellular networks should only be allowed to be dumb pipes because they are a government-granted monopoly (of spectrum). That would put them in a similar place as a utility like your electric company, sort of quasi-private but heavily regulated.

That makes sense, but OTOH utilities are notorious for stupid bureaucracy and being slow to evolve... So would they still deploy new stuff like LTE quickly? Would they still subsidize phones?

I'm not sure of the answer, but I think that's what the real debate should be if you don't want them creating "artificial fees", ie segmenting customers by value.