Personally, I think thorpe shouldn't try to appeal to young families, especially not in the half hearted fashion of adding a playground, realistically why would you go there when you have the likes of chessington, legoland and paultons as alternatives with a lot more available for kids? It just leads to a day of saying 'sorry you aren't tall enough for that ride'. Frankly there isn't enough space to make it a park that appeals to literally everyone and I think that would be a waste of time and effort.
I think there is nothing wrong with thorpe focusing on families with older kids, teenagers, adults etc. There is a market for that, but having said that they are harder to impress and with the lack of any decent additions over the past 9 years I'm not surprised by the attendance figures. Agree with above- black mirror and derren brown were way too niche to appeal to the majority of adults/teens and wouldn't be enough to draw someone to the park that wouldn't have been going annually anyway.
I think exodus with the right advertising will bring people to the park, and hopefully will have results that demonstrate to management that the park should focus on these sorts of things that will appeal to its main audience- adults, older families and teenagers.
On chessington- I'd be interested to see how these figures compare to paultons, having been to both I think a day at paultons is much more pleasant, much shorter queues, and plenty of rides for kids of all ages, so without hesitation I'd recommend to families with kids <10, I just wonder why chessington struggles so much more with queues.