Many people spend lots of money removing minerals with either softeners or filters. It all depends on what you want in the end. Really pure water will attack many materials and literally pull chemicals out of the pipes. THere's a reason why water is called the universal solvent. It can take eons, but water will attack most things. Try drinking distilled water...that's about as close to a sample as a good reverse osmosis system. It won't hurt you, but most people think it tastes 'flat', or 'funny'. You get used to it, if it's the only thing you have. To most people, given the choice of say a good spring water (which will have some minerals in it) or RO water, and for drinking purposes, they'd prefer the spring water. Now, if your spring was a sulfur spring, I think everyone would prefer the RO water!
When it comes to cooking with it, or even washing the car, the RO water, because it doesn't have minerals in it, will not leave water spots. It can let your dish washer make cleaner dishes without spots, as will using it to wash your car, too. And, it won't leave mineral deposits around your faucets or sinks or whatever. Your clothes may get cleaner in the WM. It depends.
It depends on how your 'raw' water tastes, and your final objective.