If you are an entertainer, but you play only a narrow set of roles, you reach fewer people, you have less of your art accessible to you.
Elba wasn't talking about getting skin tone treatments. He just was talking about being able to portray a more universal experience.
Schwarzenegger was an action hero actor, which placed him in a box. If he can remove his Action Hero status, he gains more access to power. But though he tried comedy (e.g. "Twins"), he couldn't really get out of the box ("Last Action Hero" was a comedy making fun of how he was stuck in a box, and it worked well).
Any actor who takes on stereotypical roles is limited. Any actor who can go beyond those stereotypes gains more power. With Elba, he's a fantastic actor, but people kept going, "Well he's black, so he should play stereotypically black roles, right?"
And if he has ambition to be at the peak of his craft, the answer should be: no, I should play whatever I'm good at.
That includes James Bond--what, is the MI6 going to reject an excellent candidate because of his skin color? Seriously?
Elba doesn't have to be carrying any pain to make a statement like that. If he wants to be known as a great actor who happens to be black, not a black actor who happens to be great--not to hold himself down to a narrower set of comparisons--then that's exactly the right attitude to have.
(He is a great actor who happens to be black.)