Currently, only unreleased albums with all officially confirmed details are allowed, which is fair enough. But why not have an extra tab or section on each band page with upcoming album release dates and other info? Also a list showing all upcoming albums from all bands would be nice.

We have a list for all upcoming albums:
http://www.metal-archives.com/release/upcoming

Regarding the extra tab, we already forbid users from adding info on "upcoming albums" because that stuff isn't of interest to an encyclopaedia. We only document stuff that's permanent, factual and set in stone. An upcoming release could be delayed or cancelled, or the band could split up before it's even finished. What then?

In either case, there's enough tabs already, and any info that doesn't fit in any of them is supposed to go in the "Additional Notes" section.