I would have to agree for the most part, this is another way for Adobe to gain more sales, the subscription does ease that pain though, since if they are pushing an annual cycle, then the subscription system IS cheaper compared to buying an upgrade once a year. But in all seriousness, nothing was stopping Adobe from releasing said publishing extensions in a patch, but hey, why give away what you can sell?
With Regard to CS3 and CS4... CS4 was a worth while upgrade, though it was forced since CS3 was notoriously unstable and offered very little extra over CS2 (anything that worked really). For many graphic designers, specifically in Print, CS2 InDesign is the best package so far because of the integrated imposition software, but rival Quark bought the company Adobe licensed the imposition suite from and since then, lost a very valuable asset to which they have not replaced since. There are third party tools available for the same function but they are an additional $200 on top of InDesign.
The Update cycle for Adobe products tend to concentrate on 2 or 3 products with key features and a couple tweaks for the rest, the sort of things you can get by without till the next major release. CS5 was Photoshop's turn with the puppet control, new colour controls, tuned GPU acceleration and the Content Awareness. Illustrator has stagnated somewhat the last few releases, it may be simple, but the only worthwhile function they introduced into CS4 for AI was scrolling in the layer pallet, it only took them 20 years to implement, but apart from that, nothing really ground shaking. CS5 brought the inclusion of dynamic width control on strokes, Alpha control on meshes, the perspective feature is still Work In Progress and very finicky, but also lots of tweaks for web graphics like pixel alignment grids and extended flash support. Premier Pro and After Effects were shifted over to 64-bit only plus GPU acceleration, but ID and DW were pretty much left out in the cold.
So the new release cycle seems to be x.0 releases will be content creation updates and x.5 release for publishing. If you don't need publishing, you don't need the new version, in which case, you can stick to the current 2 year plan. We'll see if they stick to it though since this is just assumption....
