What you describe as rpg, is actually fps with rpg elements. It's not, and will never be an rpg.
But semantics aside.
Making two modes: sandbox mode and story mode would be good, and would not need lot of work, just made all things old fans wanted: survival in voxel based sandbox game (with underground bases, full immersion, temperature, few kinds of meat, more engaging parking and cooking, action skills, better crafting progression). And for story mode just disable most of those functions and design specific quest paths for trades.
I would also love to remove traders from sandbox mode, and made quests via notes, currently traders breaks immersion.