Most parks have had a few rides that didn't last long, for example Drayton Manor had Excalibur and even Disney have had some (Rocket Rods). Fifth Dimension could be included in there. Charlie lasted for as long as Toyland Tours and Duel has been around longer than the original Haunted House was.
Parks used to want to evolve with new ideas. Great attractions used to last a fine 10 years or so, then be redesigned. It was considered a necessity to keep coming up with good ideas and keep rides looking at their best. The 5th Dimension had problems so lasted shorter, and ran off analogue technology which fundamentally became obsolete. But at the time, attractions were not expected to last longer than 10 years or so, since they entertain millions of people per year anyway.
However the parks stagnated so much, that now older rides are kept in a limbo of being broken down and old looking for years on end. This was not the case before, either they'd be redesigned with the next fun creative challenge, or they'd be restored properly to continue being entertaining. In an ideal world, you'd be able to keep all the old attractions alongside the new ones (if they were considered classics), but the space is not there in the UK to do that.
10 years was a long time for a dark ride to stay that same in those days. Even older attractions like Around The World were always being adapted (by their original designers) and having scenes added to keep them surprising. It was a very different approach they had back then.
So that is why, for example, we now have Duel lasting a lot longer than the Haunted House, despite Duel being in a horrendous state and very tacky compared to the original Haunted House. Or even look at Tomb Blaster, a very boring soulless ride, has lasted by far longer than Terror Tomb which was still very entertaining when I rode it in its final year. Parks just don't spend money on properly redeveloping attractions anymore. And that ideally means gutting an attraction after its good run of 10 years, and putting in a totally new design, not just cheaply repainting what was there before.
It's entirely subjective I supppse. However, for me, the out datedness was part of the charm. I understand that flashy and new brings in customers -- albeit fickle ones, but there's something about the old days that I miss.
Theme parks are no place for old men.
I also loved the rides you're talking about, but to be honest I don't agree with this idea of nostalgia. Those attractions you mention were great fun, they were often brilliantly designed and surprising too, but they weren't sentimental - they were immediate and funny.
The whole premise of that attraction style at the time was that it did away with sentimentality and a kitsch datedness in the UK, and got to the heart of the fun with fun personality and energy. In my memory, Beanoland that you mention was certainly not dated at its best (Dennis The Menace, a really fun imaginative kids animation in its day, was always on TV then) and its charm was kind of modern-retro, but not nostalgic. It only looked that way in its final years because of how broken down it became, after the IP had stopped being popular (this is the big problem with IP themes anyway).
It was just gutsy fun, and I think people forget this looking back, those attractions were the opposite of sentimentality. No one wants to design something to be sentimentally-appealing and dated.
Prof Burp's BubbleWorks too had a beautiful retro charm, but it wasn't done to be nostalgic, it was because it suited the theme perfectly and the ride was anything but sentimental! It was a very spontaneous, energetic family ride. Yet, looking back, a lot of enthusiasts seem to remember the ride as some kind of cutesy thing from a simpler time, which it really wasn't, it was a lot more creative and fun than that. I think attractions should aspire to be bold and energetic like that again in the future .