I base my conclusions on what I can see that makes sense.
So do I, but you are forgetting that Soliton Wave technology as seen in TNG was basically an experimental prototype in early phase.
Depends on the technology subject. Let's give HyperLoop as an example, there are plenty of good technical reasons why Humanity hasn't built a MagLev Vacuum Train / ShuttlePod system earlier even though the individual components have been around for quite a while.
Jacque Fresco proposed an even faster system with fully vacuumed trains in 1974 in his interview on Larry King.
The technology was well understood by that point and could have been done.
There were no technical barriers to execution (nor were resources the problem)... the problem was/is with the socio-economic system viewing things like that a 'massive undertaking that would be economically cost prohibitive to build'.
Also, Elon Musk got his idea for Hyperloop from ET3 - Evacuated Tube Transport Technology (a much more advanced conceptual system that would be far faster and more efficient than Hyperloop).
Its just that Musk's Hyperloop gets more recognition because he has a corporation to back him up, and we live in a world where corporations pretty much run the show.
It doesn't make ET3 less viable or technically impossible to build though, it just makes Hyperloop a priority because it comes from a corporation that is established and has a vested interest in developing Hyperloop as its own system (and not someone's else system).
Some technologies aren't worth it when there are other existing solutions, some tech can't be easily scaled down or up as you would wish.
Not so sure about that in a day and age of full scale automation, computers being able to do most if not all of the work with simple instructions in a fraction of the time.
Superluminal processing of data in Trek would result in being able to test the prototype using the vast Federation science database with latest methodologies and billions of permutations in seconds... plus with holodecks, you can easily test the systems.
Most problems in Trek propping up with new technologies is humanoids not being able to take everything into account even after saying they have. For humanoids, this is impossible, because even a specialist would contain a fraction of the knowledge that exists in their given field. A computer database would have access to infinitely much more data in any given field (which continues to evolve daily even in reality) and can access and process it far faster than Humanoids.
We are already doing this in real life by using AI and supercomputers for researching new quantum metamaterials, finding new magnetic materials, new drugs, teaching humans about art, about space, etc.
In Trek, it would be a lot simpler/easier and faster to do this via automation and get a viable/scalable unit out in a fraction of the time.
In reality (if we eliminated money and focused on what's possible from a resource and technology point of view from a sustainability POV), we'd likely cut back from 10 or 20 years it takes to develop a 'product' down to 2 years... but bear in mind that in Capitalism, it usually takes 10 to 20 years because they want to make a 'cost effective' solution that will make profits ('cost effective' by no means also means 'technically effective or efficient').
I concur, following up on "Forgotten Tech" would make life interesting / better.
Yeah... I actually liked some 'uber' technologies that were developed in some episodes but never followed up on. It showed that they can make a huge jump when they actually work at combining their knowledge and technology to find an answer... but the writers weren't nearly that clever to keep those things around because they'd have to adapt the story to suit the change in setting (which would be more realistic as the Federation would be realistically evolving rapidly in the series).
Here's an example of IRL tech that should be followed up on.
PropFan engines is one of those technologies.
You can get the fuel efficiency of TurboProps at the speeds of TurboFans, with the only downsides of louder engine noise.
We could've had this back in 1981 for mass Airline Travel. Imagine the sheer amount of CO2 that could have been avoided had this been implemented back in 1981 while making things more efficient.
Well, we had the ability to do something even better in the early 20th century.
Vertical take off and landing with fully electric planes for example - eliminating huge highways for planes and reducing overall footprint on Earth.
Tesla demonstrated Wifi power transfer in late 19th century... Geothermal energy for power and heat generation went commercial in 1911 (could have easily used that for baseload power instead of coal and tapped into dormant and live volcanoes - we even could have used synthetic diamond drills in 1950-ies to dig deep into the Earth and gain access to richer geothermal resources - and not just drills made from synthetic diamonds, but also hardware made from similar carbon materials that would allow it to withstand high pressures and heat).
If you're interested in that stuff, I suggest you google 'Jacque Fresco interview with Larry King 1974 full'. It's about 42 mins long, but quite informative on a variety of technologies that we had the ability to implement globally in 1970-ies had we wanted to.
We also had the technical ability to make massive orbital habitats in the 1970-ies for lower cost of what the USA military was getting at the time.
And, it was also possible to start colonizing the solar system at the same time (the moon I think we had the ability to start colonizing in 1950-ies though - and it would have been a lot easier to do that since it would also provide a sort of a 'jumping board' that would give us easier access to the rest of SOL).
It's not a matter of science, technology or even resources... for us (real life humans) it comes down to using an outdated socio-economic system that keeps us from making a proverbial 'quantum jump' that would make most of what we use today (and even many things we saw in Scifi) look like child's play.
Because, if we actually bothered to make those things when they became possible, it would have given us even better understanding and shot up our development further.
Unlike us, the Federation for example has no monetary barriers and can easily use its technology to make a prototype viable on a larger scale use in less than 1 year.
Remember the Slipstream drive?
The first version Voyager crew tacked onto the Warp core topped out at 300 Ly's per hour.
The second version they developed happened between 4 and 7 months later, and it incorporated Borg technology and other things which allowed the drive to achieve speeds of 10 000 Ly's a minute.
Plus, Metaphasic shielding was invented in Season 6 of TNG, and a month or two later, Geordi already implemented a Metaphasic program for the entire ship (untested, but it worked in Descent).
I think we also had other examples of prototype technologies that essentially ended up being 'complete' and fully functional versions that SF ended up using.