Hahaha, we are flying into Glasgow in April, so we might have to stop at Braehead on the way to Dundee
If you're coming to/from the U.S., there's literally no reason. The entire basis of its appeal is that it's the closest approximation to your dime-a-dozen American regional shopping mall development. You can have breakfast at Ikea, lunch at McDonald's and dinner at TGIFriday's. In between, you can do all your shopping, get a mediocre haircut, an overpriced 'coffee' and/or ice cream, and see a movie, then spend an hour trying to remember where you parked, and driving in circles, looking for a way onto the actual road, so you can make it over to Costco before it closes.
When I had two such locations within a 20 minute drive, I avoided them like the plague. Now, I want to move into one of the display tents at the sporting goods store, and refuse to leave.