Other than no-one buying it and dubious support costs. Probably a lack of compability with some weapon systems in the UK inventory. No presence for Dassault or Snecma in the UK military market and no way the MoD would get away with allowing Dassault and Snecma here when BAE Systems provides fast jet through-life services and Rolls-Royce engine support. Granted, Thales is here but their specialisation doesn't include fast jet and engine support. And would France really grant sufficient ToT of the Rafale to the UK to enable BAE Systems and Rolls-Royce to fiddle around with it unless they are really that desperate to sell it. To put it simply, the Rafale - whether it is the best plane around, the worst or nothing much to shout about - won't ever figure in the selection. And if it did, it would be right at the bottom of the list.
All good points, but has Rafale already really been entirely ruled out?
If FA18 really is a serious option, then surely any study would have to compare it with Rafale.
Or, if not, the FA18 rumour is just that...