I would pay £45 for Pleasure Beach far sooner than I'd pay £30 for Towers.
Ignoring the fact I rate the ride selection higher, it's a better value proposition.
I already go to Blackpool several times a year, so what I'd pay for hotels, parking etc is a sunk cost for me (and of course where one can avoid the charge easily in Blackpool, not least by not using a car which is a viable option, the same cannot be said of Alton Towers).
To some extent lunch is too - I can't remember the last time I actually ate at Pleasure Beach, and Wetherspoons is a relatively cheap lunch while on holiday. In either case I could not eat on park - but in the case of the Pleasure Beach doing so is simple and a load of options are nearby; contrast to Towers where the only non-park option is to pack in advance, depark, pay extra or monorail there and back etc etc...
And that sort of is the problem with Alton Towers in a nutshell value wise - you're on their estate, it doesn't integrate in to a break away (other than a multi-day trip to Alton Towers), you are entirely in their ecosystem. In Blackpool, when you've had enough you walk out the gates, stroll up the prom and you have a plethora of options ranging from free (the beach) to basically any budget (in 2p increments!).
Perhaps I'm just rich and entitled, but £40-50 for most of a day's entertainment really doesn't feel like an extreme amount for a day out in 2022. Neither is cheap, but I'd prefer to be spending an amount which is sustainable for the park without them having to fill the place to an uncomfortable extent so my 2-3 visits per year (max) are pleasant.