Though, in effect, it's no different than removinh the Niobium/Diamond route, since it'll spread activity around more. There was a discovery before the mining mod, as well, and I believe that, should the mining mod be brought back, that it would be a good idea to spread mining around.
The issue?
There aren't that many vanilla fields to mine. Kusari has none. Liberty has none. Rheinland has none inside their house. Bretonia barely has dublin.
What do we have left?
The Omegas, Dublin, The Taus, and the inexistant Gas mining of Sigma-13.
If you'd even just add Gas mining in this mod, there would be, at least, a triangular route, which will spread activity uniformely.