Milling machines, CNC machines, Subtractive Rapid Prototypers - What ever you want to call them make better parts than layer by layer additive machines.
1. No proprietary materials.
2. Real ABS, Delrin, what ever material you can find you can mill!
3. Better precision.
4. Better surface finish.
5. Lower machine cost.
Must I go on and on!
Don't get fooled by the RP bigots!