According to Area 51, Islam.SE is launched. Given that, why is the site design the same as beta design?
It used to be that a new design was a part of the graduation process. Unfortunately, as the Stack Exchange network expanded, this led to more and more sites having their graduation delayed while waiting on the new design to be developed. Eventually, the number of sites that needed a new design far outpaced the resources available for developing those designs.
Some time ago, it was decided instead that graduation going forward would be design-independent:
The Community Team announces that a site is cleared for graduation. Without delay...
- the beta label is removed
- elections are held
- migration paths are set up
- community ads are run
Then, as it becomes available:
- the site gets their custom design.
- privilege thresholds are increased to graduated site levels
As for how long until it "becomes available", your guess is as good as mine. All I know is that the community team has been stretched rather thin over the last year or so, so it might still take a while.