I actually like this feature... most of the time I want to switch to an app without it opening up docked windows. This is especially the case when switching to safari to start a new web browse. I browse in window themes, i.e. I will contain all browsing to one subject in a window then use tabs within that for the individual pages. when I want to start a new "topic" it's annoying if docked windows pop up when I switch to safari.
Here's the difference as far as I can see: Apple+tabbing doesn't open docked windows, however clicking on the dock icon to switch to the application will. I used to click on the app in the dock to switch to it and hated how stuff always came up even though i'd minimised it coz I didn't want to see it. Then Apple implemented proper application switching \o/
What OS X Could Learn From Windows: Part 2, A Consistent GUI