I'm almost with A-Kid on this one. The UK has gone for "quirky" rather than fighting a battle of biggest, fastest, best!
It's a tough one to call though. It's that conflict of enthusiast against public opinion.
Let's look at some of the "big" rides built in the last few years (rides the public will have been made aware of in a big kind of publicity push).
Colossus, Inferno, Stealth, Saw, Kumali, Velocity, air and Rita. Not a great selection to be honest from an enthusiasts point of view.
However, from the public's point of view, all have been great additions to the parks. They love either the "greatness" (Colossus and Stealth), the thrill (Rita, Stealth and Velocity) or the quirkiness (Saw and air). All these rides fit under most public preconceptions of "big rides".
I'm not even going to start looking then at the rides built in Europe and America in the same kind of time period - it's depressing.
The problem is, that these rides are public hits. They have increased park visitor numbers and had a pay back. The public really love them.
This is the problem though. Parks can get away with providing "the least they need to do" to get people into the parks. They don't need to overly push design and planning permissions as they can almost just shove in any old rubbish and the public will lap it up.
Now they're selling on the family element (apart from Thorpe). It gets in people who spend more money per head and the installations required for them are cheaper than a thrill seeker build. So again, it's money in the bank going down that route.
There does seem to be a lack of driving force in the UK actually wanting to push good, thrill rides. As the Big One proved, a massive new ride really makes a big difference (two or three million visitors over four or so years) and Stealth too has certainly put Thorpe on the map. People are happy to be thrilled, but they love to be impressed.
On the flip side, I can't complain. The UK is chock full of coasters and parks. We do have some good parks and rides too. We're not brilliant by any means, but we're a long way from dreadful. I don't know what the answer is really? Somebody with real enthusiasm for rides getting in to the management at the parks really. Somebody who knows what a mega-lite is and knows why they're so popular. Until then, we're going to have to put up with mediocre install after install...