You are right on all counts with incandescent light, but the same is not true with CFLs and LEDs. Neither of these sources gets warmer in color when dimmed. There is one exception, though, a bulb made by Eco-Story. Also, Juno Lighting just introduced a recessed downlight called the WarmDim that’s pretty terrific.
As far as energy savings go, both CFLs and LEDs immediately save you money, although those savings do not significantly increase with dimming. Dimming of CFLs and LEDs does not extend their lamp life, but CFLs at 10,000 hours and LEDs at 25,000 to 50,000 hours far outlive a standard incandescent, rated at 750 hours, and a halogen lamp, rated between 2,000 and 3,500 hours. Even if you double the lamp life of incandescent lamps by dimming them, they still have a shorter life than their more energy-efficient counterparts. I think there is room for all three sources, depending on the application and preferences. I am an equal opportunity illuminator.