Without reading all of the 17 pages, here is my opinion.
My first question is, is it that people dont drive 1/12 Mod, or just that people dont drive 1/12 in general? 1/12 is sadly very small now days.
1/12 Mod is by far the most difficult class to drive really fast in, the margins are very small and it is very easy to flip the car, thus the difference in pace between the Pros and us Amateurs, but every RC racers do not inspire to be world champion so it does not really matter.
However, I do not find 1/12 Mod very difficult to step into, in our club we had several racers who normally just do stock or F1 classes what I managed to talk into joining the 1/12 mod class, they go without any boost or turbo and they do just fine, they are behind but they take the car safely around the track driving in a good racing line. They enjoy it very much and are slowly increasing the boost and turbo when they feel confident. This is just the way I started Mod and I still do not utilize the full power (I still have battery left after 8 minutes, something the pros dont have..)
The biggest problem I find is the difficulty level of the track itself. On a track without any "dots" or "curbs" I am helplessly far behind the pros, more than 10% on the lap time but on a track with dots in the corners I can be quite close, around 2-3%.
The other issue if ofc tires, I have found that with the wrong combination of carpet and additive there are no way to go more than one run per set (Worlds race last week for example) but with the right combination 3 runs or more can easily be done.
I feel that the power and speed in a 1/12 Mod is very controllable compared to for example 1/10 Mod. The cars hold up fairly well if one drive within ones limits and the key to get a good result is not going crazy fast but to have a stable safe run. Every time I finish a run being practice or race I step of the drivers stand with a huge smile, it is just so much fun and adrenaline to run this class!
So how to get more drivers to join? I think many are just afraid of trying and need a push to actually go try and experience the fun! Maybe make sure the track layout is not too tight and that there are some margin for errors, like dots in the corners what makes the car go out of line but not flip etc. Also, the more 1/12 drivers in general, the more 1/12 mod drivers there will be..
For cost I think it is the tires what is the key, for electronics the quality demand of the parts is normally higher in stock where the motor power is the limit and every little extra power counts, in mod it doesn't unless you are going to be the world champion perhaps but that is not the discussion for today.
Amateurs will be far behind the pros, but the situation is the same when a pro take a stock car, they will still be way ahead even the cars are setup exactly the same.
I checked the race result of a random run and compared the No 1 with a middle driver in a few races.
1/8 on-road Europeans, 5% difference
1/12 worlds 10%
1/10 ISTC world 8%
Note that I really want 1/12 and specially 1/12 mod to grow, I love the class. The above is based on my view of the picture but it is limited since I mostly just do races in Asia.
In our club 1/12 stock died because everyone went into Modified despite the stock class having the MTS series with a free trip to Korea for the overall winner the class had to be discontinued from the series..
BR