I rarely use any CMYK options in PS, but their still there. Never use the file browser (unless on a Mac) but its still there. Actions panel - barely touched. There can be imageready panels thrown into PS and just not be used (or open at all). I guess something goes towards having another application under your belt and saying its free with this other app. That has a certain value to it I guess.
Since Photoshop has a slice tool (v7x), I only need to use ImageReady for animated .gifs, so Photoshop is fairly stand-alone as a web picture maker. I notice that good old “Save For Web” now says “Powered by ImageReady” (a corporate reminder).