They had barbers in FO3, but not a single one in Skyrim... why??? maybe they thought about it but didn't had enough time to implement it till 11.11.11
I doubt it's anything to do with rushed delivery. It looks to me like these cities were designed to be fairly occupied already, at their size. Most of the space in Whiterun is taken up. Which tells me it's all an early design decision, in the conceptual phase. They streamlined things on purpose. Everything is meant to push you outside, to be in dungeons or exploring. The only stores are shops and crafting stations. Which, in themselves, only offer services to make you go back outside.