I think that generally this quotation rings true, but it's also important to keep in mind that everyone thinks and everyone feels. I've always felt that there are times to just laugh things off and not take them so seriously, and there are times to feel emotion and use it for a good cause.
I mean, if someone was a total robot with no emotion whatsoever, then all of the "tragic" things in life wouldn't really bother them. Seeing people suffer wouldn't really be a big deal if it didn't affect you emotionally. So a lot of times people are motivated to help people because of the emotion that they feel.
Of course, the flip side is true that one's emotions can sometimes cloud their good reasoning and judgment. So one has to be careful to not let their emotions completely override them.
I guess I've always felt that someone's emotions should be used to inspire them to action, and ones reasoning should be used to carry out those actions.
So the quotation is true, but since everyone is a mix of both, I don't see anything wrong with viewing life as a comedy sometimes and view it as a tragedy in others. Seeing it both ways is important in different ways, and just like thinking vs. feeling as a preference, one isn't better than the other.