You’re in the right place Here’s my thoughts:
Profiles… we could ask for them for pretty much customisable program that doesn’t have that functionality already built-in. If there’s one for Plank, others might demand it for the [alternate dock-like program] too. I’d say it would be better asking the Plank developers so everyone benefits, not just Ubuntu MATE - which focuses on being modern, but retro (ie. continuation of GNOME 2).
Configurations files await in the home directory, so “states” of the dock could be compressed and shared here on the forums – perhaps a new category would work for that. That may even be what MATE Tweak does right now with the predefined panels!
You could even write your own script if you wanted to “hot swap” config files in place too.
For such feature to be added to MATE Tweak, I’m not sure if Plank is a widely used so it’ll be a very low priority request. It might be more beneficial to have an extendible “profiles” feature in MATE Tweak to add any program and preserve/restore their configuration files as a “profile”.
So just like you’d want to switch Plank profiles, a “general profiles” feature might be better - Compiz could have predefined profiles – “Eye Candy” (ie. wobbly windows), “Normal” and “Lite”. Perhaps they could be shared on these forums, or as an additional program to easily upload/download them. But I mean this can also add your own set of programs and point to where their configs are stored.