well, even in this thread all people have smooth made websites, and they didn't even apply for YC yet. Also all those companies from YC14 batch(http://yclist.com/) - they all have websites well done even for the mobile apps. I wonder why\how. Not a single team has an ugly home page

There are a bunch of beautiful landing page/single page Wordpress templates specifically gear toward this stuff. http://themeforest.net has a bunch among many other places

CSS frameworks like Zurb Foundation's and Twitter Bootstrap are pretty popular now and make it tougher to make your site look ugly. I bet that has some influence.

Majority use http://www.squarespace.com if not that, then very similar templates.

Today is easier to get a beautiful template and customize it than building something ugly from scratch.