I moved from what felt like a soulless, sweaty, concrete jungle covered in Wal-Marts and McDonald's drive-thrus to a gorgeous seaside village with rolling green hills and flowers and castles... so why WOULDN'T I want to live here instead of there?! 
((((HUGS))) Jewels! That made me feel so much better. I, for one, am dreading my impending move, but that just made me feel so inspired and excited about it.
To answer the OP. Why the UK?
I think a majority of people here have a spouse that is British and that's why they live here. My husband moved here 10 1/2 years ago and describes the way of life here "brutal." Other people have differing opinions, and some have it better than others. This is our point of view and why we are chosing to move back to my husband's country.
1. Vacations/Holidays/Sick Pay. Employers offer far less vacation pay, holidays, and sick pay than in the UK. For example, my husband will get 2 weeks vacation after 5 years at his current employer and no more, even if he works there for 20 years. I worked for an insurance company and the maximum number of paid sick days/holidays/vacation pay was 18 days (that's everything together) and they're on Forbes top 100 places to work in the US! One of the reasons they one that spot for the last 7 years is their generous paid time off! In the UK my husbands prospective employer will give him 6 weeks paid holiday/vacation time. That's a far cry from what we get here. There again, some people have it better than others; it varies.
2. The current economic situation and unemployment. If you lose your job, unemployment is not enough to live on and it runs out in 6 months. That's if you qualify for unemployment; usually your employer will contest it. After six months, you're on your own. Fall behind on your taxes, the government puts a lein on your home. There is no such thing as council housing you can apply for if you lose your house due to being behind on mortgage payments unless you are among the poorest and qualify for section 5 and you don't want to live in that, trust me.
3. Health insurance. For many it's too expensive to insure their whole families; others have fully employer paid benefits. I've been on both sides of that coin. I've paid as much as $800-1000 a month for premiums and then had deductibles as high as $1500 a person plus 20% and office visit co-pays anywhere from $10-40 depending on the type of provider. Granted I don't have to have referals from my GP but the insurance company can determine that seeing that particular specialist is not regular and routine care and deny my claim, for example. My US mom need a knee replacement surgery but will have to wait for 2 years until Medicaid kicks in or else have $60,000 of treatment. On the other hand my UK mother in law has had 2 heart operations in the last year and my fil had a bilateral hip replacement. This is not to argue the health system issues but to provide our point of view of the differences.
4. Cost of driving/cost of activities/things to do. Everything is so spread out. It costs a fortune sometimes to drive anywhere. I don't live in a major metropolis; I live outside OKC. It's big enough to have an NBA team, finally!
Culturally, though, there is little else unless you like line dancing. When my husband moved here, he thought we could be in the Rocky mountains in a few hours (its about 10-12 hours from where I live to Denver, CO.) I could fly or drive to one of America's scenic beauties but who has the cash- or vacation time? I spent it all up on health care LOL. I took my kids to the zoo last weekend. The weather was great, 62F, sunny skies. We threw down $100 bill just to treat our kids to McDonalds, the zoo admission, the tram and a cheap souvenier. OUCH! Enjoy your National Trust attractions.
Those are my husband's and my big reasons. There are other reasons. Perceptions are deceiving. The weather looks fantastic but that is short lived like anything else. Extreme weather. Tornados. Thunderstorms with straight line winds fast enough to topple trees. Lows near 0F in the winters and temps in the summer reaching 105F with 80% humidity. Mosquitos, ticks, lime disease, poisonous spiders, snakes, scorpions. Bad roads, dirt roads, toll roads. Poor schools- not poor in spirit poor in funds : ( Grass that dies in late summer. Grass fires. Volunteer fire departments that local people have to fund out of pocket (In my rural area of the county there are no government sponsored fire/safety brigades. It's funded by donations and spaghetti dinners. No I'm not kidding.). A community mindset, despite one's level of income or education, that doesn't think life, technology or culture lies outside of the United States. SUVs and trucks that get only 11 miles a gallon; cars that only get 22 miles a gallon. Driving up to 90 miles round trip to take my children to school, go to work, pick them up and go back home. Very little public transportation in most places. Public transportation that cost almost as much as commuting in your own vehicles. Trains that go to only one place and then back. Ridiculously outrageously priced daycare costs if you have children (1000-1200/mo for one full-time and two after-care children). OUCh. Those are some of our reasons
One more...He's still very very homesick and I'm ready for adventure (never lived away from home)!
