Installing dual boot over a default windows installation would be tricky, bordering on infeasible. Because you would need to shrink the windows partition live (which is not supported (and even if you could, requires free space and comes with meaningful risk of data loss)) and alter the UEFI boot entries, which is also very risky and engineered to be protected from unauthorised writes.
Even if you got around all those limitations, Windows can constantly erase your Linux boot entries (thanks Microsoft), making a dual boot-on-one disk setup basically unusable every month which needs to be fixed. So thanks to this Windows behavior, this setup won't work on many systems.
So you'll pretty much only ever be able to install to another disk. And the portion of non-tech savvy users with a spare, unused disk is going to be effectively nonexistent.
Don't get me wrong, an install-from-windows feature would be nice, but I don't think it could feasibly overcome any meaningful barriers.