They certainly are not a big deal where I train. But the instructors have expressed that they feel it is important for us to at least know how to take a breakfall should we need to do so. Perhaps in our own dojo a breakfall is taken only because uke chooses to. (I happen to really like them) but when at a seminar or visiting another dojo one might end up training with someone used to taking and therefore throwing people so that a breakfall is necessary.
Personally I think its a handy skill to have on the off chance my horse sends me on an unscheduled dismount.