All Impreza sedans don't have fold down rear seats because the chassis has massive cross members going through there for the sake of rigidity and integrity. The only thing they get is a pass thru hole.

Sunroofs also reduce rigidity, even factory ones, because a massive thick crossmember usually connects the Bpillers together (plus several smaller ones for roof sheet metal stability). The sunroof, while it does reinforce the cut members, is no replacement for that Bpillar crossmember. How do I know? I had an aftermarket sunroof put in my WRX and I had them save me the cut members. The factory ones have a replacement member integrated into the sunroof cartridge, but it's not nearly as beefy as the original.

Subura rally heritage means it values rigidity.

And unfortunately, yeah, daily driving is opposed to this because then you really need sunroofs and fold downs.