My own personal reasons ( I still work and it's not economically feasible to tow a trailer 2,500 before I even cross the border for a five week vacation) have me touring Mexico by motorcycle now rather than an RV.
I still see value here, roads, cities, things to do whether I tour on two wheels or ten are relevant.
It's my opinion that RV travel in Mexico is dwindling. I rarely see rigs on the roads in Mexico and campgrounds I used to use are closed. A few new ones open, but the trend is downward.
I don't think it's a forum failure. Things have changed:
1. Fuel - gas or diesel while cheaper in the US costs dearly in Mexico.
2. People have changed. The sense of adventure has changed - people have become more docile, less willing to think for themselves. News from Mexico is almost always negative, that discourages people.
3. Commercial jets have become flying buses - people seeking foreign travel are more likely to go overseas.
4. People are more likely to float around on a cruise ship than they are to buy an RV, maintain and drive it - especially in a country with few RV campgrounds, narrow roads and expensive fuel.