I'm also in favour of the incredibly cheerful perfume a Christmas tree brings to one's home, but... the same trick can be achieved by just a couple of branches, which also look delightful when decorated, instead of the whole tree. It doesn't have the same harm on the environmnent, imho, it helps explore one's creativity and it helps educate children in an environment-conscious way.
Also for the creativity and education part, a real fun is to make your own christmas tree out of recycled materials (plenty info on the internet).

IMHO, the argument "plastic ChTrees are more harmfull to the environment" should be stopped at this point and not continued with "thus we choose a real one instead"...

And afterall, Christmas is not about the tree, is it?