Maybe I haven’t seen such docks (the one I use with my work laptop has a pretty short cable that is not suitable for sitting somewhere off to the side with the actual computer on my lap), but even so, that would at best be one less wire… and much less convenient, because now if I want to plug something in, I have to reach for a second box that isn’t conveniently right on my lap. And I have to find somewhere to put the dock.
The mouse really ought to plug right into the laptop, or at least right by it.
Really, the only way I could see that working would be to have the laptop sitting on a tray that the dock also sits on, effectively turning laptop plus dock into one “unit”. Please, just give me double-height expansion cards. Six or more ports (I think a taller card could fit up to three ports, turned vertically?) is probably sufficient. Four is in “what do I have to do without?” territory.
As someone else said: