Most plugin UIs are extremely simple compared to a DAW, and have the nice property that most of the time they aren't visible.
I stand by what I said: most plugins have nowhere near the complexity of a DAW. Some do! (Kontakt/Reakt, and so on) but the vast majority only have a small subset of what the DAW needs to display, and only need to do it for a limited number of channels, and only need to do it rarely.