I hardly think it's missing a trick to not offer an exchange. The Pro is not a 'replacement' for the RT, nor an 'upgrade' - rather a separate model. It's a little like a car company offering owners of the petrol model of one of their cars a trade-in when the diesel variant was released. (Please, no arguing over whether Petrol or Diesel is best!!). Think of the message it would send to offer an exchange for Surface RT owners - it would be an admission that the Surface RT (and by extension Windows RT) had failed, and would likely kill the product line!
The primary practical difference between the RT and the Pro is that the Pro will be able to run regular desktop software. Granted, Microsoft have not done a good job of communicating what Windows RT can't do, but buyers of the Surface RT quickly discovering this limitation* should be calling Microsoft and asking for a refund sooner rather than later. Keeping hold of the device and waiting for the Pro version for a potentially long period of time is not a smart move, as a company is hardly likely to believe you were 'unhappy' with a product - but didn't send it back right away. Remember, UK law (guessing based on the currency you used) does not offer you any automatic right to a refund; that's down to the goodwill of the company you bought the product from, and whilst many companies will often extend such goodwill if you are reasonably prompt about asking for a refund ... keeping hold of the device until a different one comes out and then saying you're unhappy with the one you have is unlikely to yield results!
If you really want to exchange for a Surface Pro, your only real choice is to try and see if Microsoft will accept the device back as in some way faulty, or just call Microsoft repeatedly until you get hold of someone who will give you a refund ... my guess is you'll need a lot of luck!
* I should note that I personally don't feel this is a limitation - I own a Surface RT, and went into it fully knowing the capabilities of Windows RT. I use it as a tablet computer, and as such find it to be the best tablet out there! If you want a Tablet, buy Surface RT, if you want a full PC hybrid, buy Surface Pro