It’s worth pointing out that Oakwood have also made cuts to their opening hours over the years.
Pre-2009, the 10:00-10:00 opening hours took place every day in August. In 2009, the late night openings were totally scrapped for two seasons and then in 2011, they returned but only for two nights a week in August, a model which I believe they’ve stuck with every summer since.
Oakwood operate these late night openings in the summer only because the park is in Pembrokeshire, one of the UK’s most popular tourist counties. Pembrokeshire explodes with visitors in the summer holidays, but is a pretty dead affair the rest of the year. Oakwood’s hours reflect this as the park spends most of the year opening only at weekends (or just Saturdays in Sept) and, on these days outside of summer, the park only opens 10:00-4:30.
People seem to be comparing Oakwood and Alton because they’re both in remote locations, but this is literally the only similarity the two locations have. In every other way, they’re two completely different places.