I’m Fx user, but I’ve to agree. Also, generally, Mozilla’s Addons page is very bad designated. And they just re-designated the site… I don’t even understand how such a bad design found it’s way…. Generally, they’ve old, bad taste in design almost on everything.
If we take every link that leads to one of the many Mozilla’s sites, only this design I like by them: https://developer.mozilla.org/en-US/