I understand this may be a controversial change, but we didn't make it without lots of discussion and measuring.
From a limited amount of user testing that we did, we knew that we had a problem with brand-new users being confused by our homepages. They didn't understand many of the menu options; couldn't figure out what the difference was between week, month, hot, and active; and ultimately had trouble even figuring out why they might be interested in the site.
We also did heatmap tracking and found that very few users bother using the sorts, with clicks on "month" practically rounding to zero, not because it's useless but because it's not obvious what exactly it does.
I realize that we have two main audiences on the front page: anonymous users and repeat visitors that are not logged in. We had to make a choice about who exactly the homepage should be focusing on. We decided to focus on anonymous users.
Thus, we added the hero banner, removed some menu items that we thought were redundant and/or not relevant, and changed the question list to use only one sort and added a "tag cloud" of sorts at the top to help put interesting keywords right in front of users.
The numbers show that this has been successful. Visits to the about page are up about 400% total, browsing engagement – measured by clicks in the question list – is up a couple hundred percent, and about 7% of visitors to the homepage click on one or more tags to filter the questions list. In short, people are browsing more, reading more questions, and even answering more by a small percentage.
I realize that our sites and communities are more than numbers, and I also realize that we're squeezing users who a) don't want to register and b) are registered on another site but don't want to log in on the current site.
However, from a purely objective standpoint, users who browse but never vote or post just aren't really that valuable, relatively speaking – except to encourage cross site discovery which we intend to incentivize in other ways. We want to encourage logging in or registering (which can be done through an anonymous open ID provider if one is concerned about privacy) which amounts to a fairly quick and easy off switch for these changes.
Completely separate from all this stuff is plans to make the registered homepage and questions section more flexible and more customizable for registered users. We just haven't specced out those changes yet.
Further, adding SSL support sitewide is imminent, and after we have managed that, better support for logging in – and staying logged in – across sites will be easier.