I think there are two sides to it and I can agree with both. On one hand having less makes them feel more special but on the other there's still a limit to how many you can have even when you really want them. I think it's good to be a bit in the middle I suppose.
I can't see myself filling up those pet stable slots at all. I haven't done that yet with the current slots even. But I think it's good to have that space just in case if you do indeed want a little more of that room for those special pets.