The change is intentional. See the wiki edit (by Jackk from Trike).

It's gone for me too, but I don't think it'll last. This has happened before, and I think we're looking at either an intermittent glitch on the server side or some kind of resource issue.

Personally, though, I'd be just as happy to see it stay gone. It's ugly; it takes up real estate it doesn't need to; and most importantly it's not all that useful for its apparent niche as a guide to newcomers, adding little that the header bar doesn't already have. The article lists aren't too hot either; the stuff they link to is usually years old and the aggregation function seems to be doing some kind of dumb association that usually clusters around some uninteresting keyword. I liked it better when the front page just mirrored Main, although aggregating Main and Discussion might be a better move these days.