As far as falling on hardwood floors and such, I feel that everyone should be able to perform rolls comfortably on them. Being able to breakfall on hard floors is nothing spectacular, really. if I do a regular slapping breakfall, my hand and arm stings for a bit; if I do a "soft" breakfall (like you may see with some Yoshinkan people), it's not that uncomfortable at all.
Jun, you actually make a good point in that it can be done. We did it at the place I mentioned and all in all I admit to being stunned at how well. I've fallen a number of times on concrete while playing basketball and riding my bike and all but once came up fine. The one-time I didn't I went over my handlebars with almost no speed and almost landed on my head. As it was, my neck and bike were royally tweaked. I could have been hurt much worse and probably would have were it not for the fact that I was comfortable being upside down.
Still and all, I'm with the sempai mentioned above.