It is interesting to hear your views, but I must disagree with you on The Smiler which I believe has been designed with a theme in mind. The reason I say this is because of the strong marketing campaign The Smiler had. This included the 'Smile. Always' YouTube series, links with 'The Sanctuary' maze and the 'Ministry of Joy' tie-in for X-Sector to name just a few things. Looking at the mood boards, it is clear to see the theme and I believe some images from these are on display in The Rollercoaster Restuarant. Unfortunately, the backstory has been lost more and more since 2015 and I do believe that normal guests do not understand the theme as well, which is a shame, although the industrial and sinister feel still remains.
Oh yes, The Smiler certainly has a great theme that people can enjoy, but guests aren't supposed to be understand the backstory or know it. As a part time designer I see how concepts are created and a ride's theme design made. When a theme is created, there needs to be a written brief so that all the designers on a project can create towards that. If it wasn't a good written premise that leant itself to a good ride or a good atmosphere, then the end result would be a bit of a mess. I think this is the trouble with Thirteen - it had a good beginnings of an idea but then wasnt delivered. The "abandoned race track" idea is just something that was tied together afterwards to try and "make sense" of why there was a previously themed racecar ride next to a haunted forest themed coaster!
Sometimes enthusiasts, when they read things on the internet or watch videos, etc, can miss the point of what a backstory is. The Nemesis one was excellent because it gave a good, unique premise for the designers to create the look of the ride, the view points and the style of it. But the end result is what is intended for all riders to experience and to capture their imagination, not the backstory that was written for the design team to be able to create it.
The Smiler's promotional videos tied it into the Sanctuary just to create a PR build up and weren't really anything dependent on the finished ride. You could remove all references to Dr Kelman or the "Ministry" and the ride would still be just as effective for people to "get" the theme, because the style, colours, designs and energy of it works well. (..Until you enter the very empty building though!) Alton Towers putting signs up at the entrance to X Sector in an attempt to tie it in with the rest the area just missed the point of what makes a fun ride for most, it's like trying to explain something literally instead of letting guests' imaginations create the feeling for themselves in what they see, hear and ride.
If you actually have to go on the internet and watch some low-budget promo videos to 'get' the ride then it doesn't work and it shouldn't be that way. The Nemesis video is often taken too literally when it was made just to promote the ride in its first year. The Nemesis that guests walk down into the big quarry with the beastly ride all around them, and the weird cultish/alien atmosphere of the area - that is the real thing that was intended to be experienced, and the real 'story' behind it can be anything that your imagination conjures up, that's the idea.
Also putting the videos into the Nemesis Sub Terra queueline was just an easter egg for enthusiasts, I don't think it was done in a way that the public could be a part of or enjoy. I wouldn't call it accepting their heritage, the team that wrote the original Nemesis video would've been a different (external) team to that designed the ride, but both needed a 'backstory' to write to so that it added up.