I have to say that for me the desire to make square or close to square photographs came before, and drove, the acquisition of a 6x6 camera. I've always felt uncomfortable with the angular shape of 35mm and if I hadn't then I'd have bought a 645 camera, because cropping aside its easier when your viewfinder is about the same shape as the images you want to end up with.
So whilst I'm sure that it is possible to "get used to it", does the fact that you have to work at it, or might crop a majority of your photographs as some do, mean that you have the wrong format? Whilst one's judgement of what works and doesn't work will surely improve with thought and practise, I wonder whether it will get to be as good as using a format in which tends to be most natural.
Personally I crop less than 5% of my photographs. That isn't because I resist cropping - its because I'm working in a format I've felt comfortable with.