Opting out
could have considerational merit for lots of people, in principle.
Having a beefy promotion late in the day could create a liability with a skewed annual allowance/defined benefit liability that you might want to place instead, with a personal scheme that offers you more flexibility and unfettered, earlier access.
To see why the country is so stuffed, if you're bored, here's my blog from last year commenting on the UK WOG accounts. The next ones (this year's) will make for interesting reading. Well, I say interesting.
Al Rush | Wanted: Bill Gates and 40 of his just as successful mates