Why?
New York is an enormous city with many people interested in all sorts of things. There are well-publicized events for every topic, but hundreds more that go unnoticed despite the excellent content and enthusiastic organizers.
Things are largely posted on individual pages, which require you to actually come to the page to learn about an event. The benefit of a calendar is that it puts everything right in front of you.
Why yet another calendar?
Mostly, it’s the difference in the types of events. For example, Noah Greenstein’s excellent calendar (a large inspiration for this one, actually) focuses on larger, institutional events usually connected to a university or a proper academic group. Also, I personally enjoy using a tool without fifteen thousand ads and a mandatory account, and at this point the only way to get one might be just to make it yourself.
Why are there so few events?
Because I put them in by hand, and generally only list what I know to be a reasonable event by well-meaning organizers. Also, I don’t currently intend to list any paid events. You can help alleviate this if you have an idea in mind. Just go to the Contact page.
Why is it so ugly?
Because I’m not a web designer. Suggestions are welcome.