We try to do randori whenever we can, but there are so many things you think -yeh, we should do this every session, that you can't always squeeze them all in.
I think it's great practise for timing, body movement and awareness. It's much harder to do than staged techniques (especially if there is more than one attack type), but for this reason I think people should get a reasonable amount of practise.
I think that sometimes randori can be scrappy and unrealistic if the reasons behind the practise are not understood. Also, it is important to have good uke or else injuries may occur.