It's true all major new attractions need to see a decent return, because of their huge cost if anything. But I suppose the difference is Merlin invest only for instant hits, they never invest in the value of the actual park, beyond basic maintenance.
Big money gets invested in headline rides, anything else is sidelined. So other than new rides, the state of their parks is pretty poor, including not investing in proper operations to keep queues down and generally not creating a place to be. Then their new rides are also left to decline once they've stopped serving that instant return. Even when new land is added like the Swarm's island expansion, it's just a minimal dead-end, when it had opportunity to add much needed value to the park and create more throughfare.
This stuff all has an impact on guests experience. But Merlin's marketing depts still think yet another quick 'rebrand' with new signs, music and logos will do the trick, instead of proper long term investment.
Icon at Blackpool was more beneficial to the park's overall value I feel, as well as a headline attraction for that year. It should have been advertised more (beyond the previs videos on BBC that made it look boring!), but it adds a modern element to the park's offering, making the Pleasure Beach a much more rounded day out.
I hope BPB sees increasing appeal from here on and gets back on track, but it won't if it lets the momentum die.
Looking at parks abroad that began the same way as Thorpe Park in the 70s/80s, you can see how they've taken a much more holistic approach over their history and today are altogether much better places to visit. But Thorpe Park has become so confused by cheap rehashes and short term investments, that I feel it doesnt deliver a solid appeal with many people anymore. Other than Derren Brown, which was probably intended to be a long term investment in the park, but because of its bad development it ended up so esoteric, with costs so out of proportion to its actual entertainment factor.
I agree that stronger focus on good events would really help the park. Fright Nights still excites a lot of people in the region, but then why is it getting worse each year? Why is it advertised so much, but then so minimal in reality? You could have a far better Halloween event almost anywhere else, like the brilliant events at farm parks as mentioned earlier. You actually need to put the focus on entertainment for once, instead of the lazy minimal approach currently.