This isn't surprising, and I'd almost isn't really a sad moment for Roy, either.
I look back to Larry Wilmore, who had a moderately successful show that was abruptly canceled. It wasn't perfect, and I had my issues with it, but I'm a sucker for a solid panel discussion segment, especially if Bill Maher isn't the one leading it.
The reality is that they absolutely could have built off of that show if they wanted to, but they did not want to. They wanted the spiritual successor to Stephen Colbert without realizing that you don't get that overnight. But on top of that, they definitely weren't going to chase it with a black host. Yes, Trevor Noah was black, but he was also "safe", and we know this.
Moving to Roy, IMO he absolutely deserved a shot at hosting the Daily Show. But due to a lot of factors (race being a huge one), he was never going to get a fair shake when they could go casting for a different demo or a bigger name pull. Roy is absolutely right to leave, and probably leaving at an incredibly advantageous time. So many other talents from that show have moved on the bigger and better things, and there's no real issue with him taking his shot at that, too. On top of that, he was civil as hell about it, and no one can really blame him moving on to something else when the big chair isn't going to be you.