I have been diving Enriched air/Nitrox, for most of my diving career. I also ended up in the chamber in Cozumel with about 475 dives under my belt, and no definitive reason as to why I ended up with skin benz type 2 with neurological involvement. I had 5 days of chamber treatments.
I now have a little over 700 dives under my belt, and I always recommend Nitrox to everyone.
When we go down to depth, our computers/dive tables, are basing calculations on theoretical numbers, these numbers came from young healthy individuals. When we are under the water, we don't have wires directly monitoring our nitrogen load.
All of our bodies off gas differently. As we age, our bodies are less efficient at releasing nitrogen, also bone density, scar tissue, fatty tissues, make nitrogen harder to release.
Diving enriched air reduces the chance of getting nitrogen narcosis. Clearly there is no guarantee.
In addition to the above, you can get more bottom time, shorter surface intervals, and you feel less tired. Personally, I don't use it to extend my bottom time. I use it as an additional precaution.