My reasons were because of the huge booooobies that made me uncomfortable. I had to have my whole boob out to feed and it was impossible.
Thats pretty much my reasoning as well for feeding in parents rooms. I can't just "discreetly" feed - when you have size G breasts it is near on impossible!!!

Also quite often if I have a toddler with me then it is easier in a parents room as then the toddler can wander around a bit without me having to worry that they will get up and go and I will have to chase them with my boob flopping out!

I have b/f out and about in restaraunts etc and have no problems at someones house, playgroup, etc but if am at the shops and there is a parents room available I will use that option.