If someone did a bunch of stuff that was legal at the time, but that stuff ended up being all of the planning done for a murder, would you have the same opinion? Honestly you seem to be suggesting there should be no legal difference between 1st and 2nd etc degree murder as long as all of the little widgets of planning were legal when they were done.
The point of our laws is not only to prosecute and punish. They also reflect what we as a culture and society will tolerate (Durkheim). Having a law against hate crimes tells people that our culture will not tolerate hate crimes and I'm 100% here for it.