I agree that markup is easier to write - it's shorter. And typical html is much messier. But if you wrote html the way you did markdown the difference is much smaller. In fact - look at the OP's text. That article in html would be barely longer.

To summarize: markup is better to read+write. But the difference is almost zero. Anything other than trivial markup is a mess; exceptional layout often impossible (and I value the ability to creatively use layout to get my point across). It doesn't support wysiwym editing (very well). It isn't trivially statically hostable - and if you try it's fragile and flashes uglily. Many flavors exist that are slightly different.

I prefer flexibility, consistency and simplicity over micro-optimizing source readability.