Its not the freedom that is the problem. Its the lack of substantive consequences. That is the issue. Bethesda always wants their games so some people can do absolutely everything there is to accomplish on a single character.
For me the game starts becoming boring at around level 30-40, also with my second character. 250+ hours into the game, I have yet to complete a faction questline. My biggest problem is that I level up too fast, or the benefits in the bar stats are too great. Splitting the bars for health and stamina, with just a few into magic - by the time I reach high level in sneak I no longer care about the perks it gives (like pressure plates). All scaling seem to revolve around the foes, not the rest of the gameplay. And yes, this is on master already, although this time I don't release the dragons.
Note that I am paying for skill increases that doesn't seem to skill up naturally (as an archer relying on alteration for magic protection, alteration and light armor doesn't seem to progress at all).