Just because you/your dc/your dog didn't have a en-suite doesn't mean that she can't feel hurt if it's taken away. Taking it away is very different to never having one. And yes, it is her parents' house and they don't own a room, but it's the room she has been given.
I mean, let's say you phone up to book a room in a hotel, and they say they'll give you an upgrade to the best room with a balcony etc. You arrive, looking forward to the extras, and they tell you they decided another guest could have it.
I suspect most people would feel indignant and feel it had been taken away.
But if you'd not been told you could have it, then you wouldn't have considered having it.
Now in both you're in exactly the same position you paid for, but in the first you feel you missed out on something.
Surely you can see how that is different?
My (very loving) parents on a couple of occasions decided something of mine was going down to my brother. I was the middle one and at the time there was very little difference in size between me and him, but I was much smaller than my older sister.
I particularly remember when I came home and discovered my parents had put stabilisers on my bike (which I rode regularly) because my brother's bike was getting a bit small for him. The next size up bike which my sister had finished with, was far too big for me.
It hurt, and the hurt feeling, stayed with me, and made me feel as though I was less important, and certainly that my feelings were less important.
I remember mum saying "but surely you realise how important it is for him to have a bike". But now I didn't have a bike - in fact it would have been more suitable for my brother because he had stabilisers so not going to fall off.
I had the smallest room, slightly bigger than a box room at home all through until I left home. I also, for very odd reasons had the spare wardrobe in my room, leaving me with about 1m^2 floor space at best. I couldn't even open my wardrobe doors fully.
My sister had a room about three times the size, and my brother's was almost double.
But I never minded, because that was the rooms we had been given when we moved in. It never even occurred to me to mind.