It is 100% Sky's fault.
The mistake WWE made was signing the new deal with Sky... They had gone for a "big deal", Premiership Footbal level and didn't get it cos Sky played hardball. It was part of Vince's grandstanding at the time and it backfired.
The change they allowed was for ALL PPV events to be, well PPV... previously we got 4 a year "free" (bear in mind Sky is subscription to begin with) without additional cost. Those were removed.
So when the Network came along, Sky once again played hardball, there was one night where RAW was "going to be pulled" for example hence all the delays in releasing the network.
The concession was that they didn't "compete on price" with Sky, who had been charging £15 to watch a PPV. I would imagine they agreed the £9.99 price point as one that Sky could also charge and not be "losing too much". Bear in mind as well, the UK gets screwed on ALL products, Itunes, consoles, literally everything is dearer here, cos companies can get away with it.
In terms of WWE itself, they don't "screw" the UK intentionally, indeed the Network farrago saw Vince at his most concilliatory, when has he ever come out to personally apologise to ANY fans other than over Benoit's tribute?
The reality is time difference - Beast in The East worked as it was a novelty and 4th of July/saturday anyway. American fans AND European could watch pretty much the same time give or take 2 hours. London's timezone doesn't work that way, a PPV would have to be so late to air "live" in the US that it wouldn't be allowed for zoning reasons. All stadia here have strict rules on curfews cos there are always neighbourhoods nearby. Getting 100k people out of Wembley at 1am, when they have work/school etc in the morning along with the natives is a logistical nightmare... so it has to go earlier in the day, which means a delay and spoilers. Plus the Americans would hate it... genuinely, if Mania ever came here. Could you imagine the butthurt from "bidding cities" and the like? It'd be like The World Cup/FIFA debacle with Qatar.
Wembley also has a maximum quota of events for a year, with many being taken up with NFL until the new Spurs stadium is ready in 3-4 years time. Other grounds could hold it but they're not as "sexy" as Wembley... If WWE was serious about Mania, Summerslam or my choice, The Rumble in the UK, it HAS to be at Wembley.
I think realistically the earliest you see it is, if possible, Summerslam 2017 - 25 years after the first held there, it's a realistic goal for WWE.
The opportunity WWE DOES have however is to truly make Wrestlemania a weekend event. a 2 day PPV - London on the Saturday, MSG on the Sunday with somebody main eventing both nights... hell you could even run them the same day with a short break... Imagine the first 4 hour show going out from London, a title match opening and the winner getting on the jet and wrestling the main event at MSG 7-8 hours later... If WWE wanted to make Mania a truly global event THAT might work.
The other "problem" is that the UK wrestling scene itself is quite small still, despite the high numbers of talents from UK and Ireland getting into their system, there is no feeder feds as such, the closest to a televised promotion has been ICW which got a BBC documentary.