It's one thing to be able to emulate DOS games (something which worked 20+ years ago), it's another thing to offer reasonable ergonomics in a modern environment...
It is of course possible to launch games from outside of DOSBox the way GOG does it, using host OS (non DOS) launch scripts and config for each game, but I prefer to have more like a virtual DOS fantasy console with all games installed. It also means DOSBox is fully self-contained, with no dependencies on the host OS. Once set up there is no maintenance. There is no code rot in DOS of course, so when something has been set up it will always work.
I want the window to be open like any other window, and the mouse pointer to work transparently in and out of it - like when I hover the mouse over the dosbox window, change the pointer but keep the same mouse speed, momentum etc
I think this would be really hard to do in an emulated environment, maybe even would require patching each game executable to get the mouse speed right (not sure?), the modern environment integration, like you say, is what Im after too