Lukas, you know that Wayne&Wes Weber did practically the same thing
a few years back with an EX500 twin in a custom frame?
The new Versys engine is the logical next step in that direction. A compact, easy to get twin in a dirt-worthy package. If you really want all the headache of stuffing a motor in a different frame, by all means go ahead. It's an extremely sensible idea and the factories are offering nothing like it. Either it's heavy and road oriented (Transalp, Versys), too highstrung and service intensive (Aprilia) or too big (990, HP2).