I don't think it should be mandatory. The arguments that I've heard here today and that I read in the newspapers for keeping the mandatory long form seem to me to boil down to, well, the information we get from this is useful, and if we changed it we wouldn't get quite as good information; it might be a little less useful.
I don't think it's the government's job to do everything that is useful. I think human beings should be free to pursue their own goals, their own aims in life, as long as they don't interfere with other people's freedoms, as long as they don't use force against other people. I think the idea that this is useful and therefore it should be mandatory is basically saying that my freedom is inconvenient to the government.