[dogscoff]

Later in the game radioactives become far more important for things like stellar maniuplation. Organics are important for organics races, and for a few of the more obscure components and facilities.
But basically, yeah. In the standard game, M rules and O&R are only good for trading with the AIs. (Or for feeding into your resource converter.)

Once you start playing with mods, however, O&R come into their own. Proportions, Devnull and P&N all have more balanced resource costs, and probably other mods as well.