I also believe the Tony voters are savvy enough to refrain from voting for someone just because they're "overdue," etc. Even if you did want to suggest that, it's been a long time since KC got her Tony. So she's still only one ahead of KO. It's not like she's Audra McDonald when it comes to nominations and wins. 
In the end it should be for the performance at hand. The overall performance.
I will admit that I was a little surprised by O'hara's quote when I read it too. But maybe she's just being honest. Which is great. I had mentioned something similar on another thread, having noted that I've seen TKAI numerous times and think it's a fantastic musical with amazing music.
But after seeing Chenoweth in OTTC, her role just seems a lot more complex to me.
True that Anna has to be played by a great actress. And KO is exactly that.
But so does Lily.
Add to Lily…comic timing, and a great voice.
Interesting how it's the latter of which that KO plays down a bit in the quote relating to her character.
What a season! Great actresses. Many things to consider.
I still wonder if we don't see the Tony going to Chenoweth, with revival going to TKAI. Sharing the wealth a bit.