No doubt evasion is a good tool in reducing REFLEX based damage. However, more valuable then evasion is a good REFLEX save.

Poor reflex with evasion, the evasion is wasted - There are better places to spend the feat...
Good reflex with evasion - You will have few times where you take full damage
Excellent reflex with evasion - Reflex damage, what reflex damage?

If however, your saves are so good that you are constantly only taking 1/2 or less in damage and your ability to self heal through it makes it so that you can laugh it off, it is possible that evasion is not the best investment.

One advantage that those without evasion have is that they have an opportunity to learn how to mitigate the damage and utilize these other tools that help them by improving their reflex saves and managing the damage that they do take.

My advice is to never plan a build with evasion without planning how you are going to make their reflex sound. If not able to access evasion for a build make sure that you manage your reflex and other tools to minimize the effects of REFLEX damage.