Timebuilding in the USA is very popular and rightfully so because:
Girly bars
Hooters
Good shopping malls
Seriously though, your point of more airspace where you will actually learn something I can't agree with. I totally agree that it's value for money flight time there, but experience in Europe prior to CPL training is more of a benefit to a low timer rather than operating in US class B etc. As far as speaking the same language, I'll never forget the first time I worked Boston centre (sorry, center!) after an Atlantic crossing... Hopefully the next generation of FMS's will have google translate!
On the other hand, if the candidates intend to do the CPL test in the USA then possibly a different issue although they would still have to learn UK or other European airspace for the IR test.
It's what's best for the individual students, I'm sure you will agree. I personally enjoyed light aircraft flying in the States although I was not hour building. Such freedom. Naples to the keys was always fun as was the 'space shuttle tour', and no night restrictions or costs to worry about.