Honestly, there are good reasons why content should be spaced out that are not "increases subscription time" - it helps fight choice paralysis, for example, or funnels a greater number of players in a singular direction, which means content is more populated, which also reduces queue times. The problem is not the spacing out of the content itself, its the amount of shelf life / play time the content has, the cadence of updates, and the variety of content offered.

When CS3 frontloads "one and done" kinda of content in an expansion, and plans to release longer shelf life content further back then of course people will feel like there is nothing to do. Releasing everything at once would bring different kinda issues really.