Actually you could travel to more cities and towns with the travel system in Morrowind than you could in Oblivion from the git-go, meaning you didn't have to walk to or discover any of those. Divine intervention meant that you only had to walk halfway toward a place with a chapel or temple, and you could teleport in. Your added depth from that angle is phony.
Well, as far as cities go, it's realism, plus you have to pay for it. Intervention spells asked you to having bought them, or be able to cast them. I don't see how it's no added depth. Oblivion just had you teleporting to anywhere you already been, including every single fort or Ayleid ruin. And could you fast travel to a city you haven't been before?