I think the proximity of Gleneagles is part of the reason they are keeping the hotel upmarket. People on golfing holidays will want to play there, but many won't want to stay there. It's previously been a "destination" venue for people to go for a nice meal, weddings and weekends away. One of the main criticisms of the previous incarnation was that it needed a facelift, and that's what it's getting.
It's the wrong venue/location for a budget hotel, and not nearly enough rooms for that to be viable. With the management company involved (ICMI), they'll know how to keep a handle on costs, and how to pitch prices at the right level. I'm sure they've already done a lot of sums before the deal was finalised and making the announcement.
Here's a link to the ICMI website, so you can read more about them and the other hotels they manage. http://www.icmi.co.uk/aboutus.html
The article in the Independent was interesting, and it's good to draw attention to what Andy's peers are investing in, but it's spectacularly irrelevant that Andy's spent less on buying this hotel than Rafa is supposed to be spending to remodel a couple of properties. Andy bought a local property that was available, and presumably at the market price, not as a means to show off how rich he is. Not only that, but the purchase price is probably only the half of it.
It looks like the hotel's contents weren't part of the sale. These are being sold off separately by the Eden family at an auction next month. http://www.trscottishauctions.com/2013/0216/index.html