I have discovered that in completing the Quests and with Exploring etc. you level to a higher range of tasks and different area (e.g. from Glenumbra Stormhaven)before everything at the Level range for the tasks is done.
Zenimax have obviously realised that because Ultimate Abilities do not build when completing a task/quest that is lower than your level range.
As I see it, that spoils the quests as they are not played as originally intended.
It would be good if a player could delay levelling i.e. although it is already possible to save using the attribute and skill points gained. The level increases and that causes the Ultimate Ability nerf. and higher level quests start.
Therefore in my opinion the Level should not be raised until the attribute and skill point gained is used.