Very true. It is not suitable for desert. But before Koleos, I never thought of driving off-tarmac. When I got it, I started to think of driving offroad. Soon after I got beaten by the offroad bug.
On the other hand, driving it on sand was a great challenge and I was giving my %100 at all time to cover up the absence of a proper 4x4 system and existence of electronics! When I switched to Trailblazer, it felt relatively easier.
I believe starting with Koleos gave me an important experience because of the challenge.