Did you follow the link given by OP? The one about C++ and its properties and the problems that come with it?
There are problems connected to using C++ as the main language for something as central as the preferred toolkit. As simple things as using a debugger can turn incredibly ugly even with moderately sized projects on account of C++, by design, being hard to interpret in object form. That in turn results in harder to debug programs which leads to lower quality code and that's a pain no matter how you look at it.
C++ being taught in schools is not an argument for it being the best choice on a device like the N900.
With that said, Qt might very well be the best choice when it comes to application development but it is, in my opinion, a pity it's implemented in C++.