You can look at it as everyone is "limited" to their type. The questions you want to research are:
1. How many people am I competing against with weird colored hair?
2. How many casting calls am I seeing for people with weird colored hair?
3. How many roles do I see on TV or in films with people my age/gender with weird colored hair?
Then you can decide if you want to go with the permanent color, or the trendy wash outs.
Bottom line is, you want to feel true to yourself and confident when you are auditioning. If your headshots are captivating, you could get called in for a role that didn't call for weird colored hair, just because the Casting Director wants to see your take on the character.