Man, pretty much every dev out there struggled with HD development, especially the entire Japanese dev scene. For devs like Nintendo it took almost an entire gen before they could develop HD games at a reasonable pace. "Just the resolution". I don't think you know what you're talking about here, sorry.
It is all about how a dev can scale the content down to play on a console. Typically devs make the assets at a large scale and have to remove resolution to fit it at 4K or 1080p or 60fps or whatever their goal is. Maybe every dev struggled with HD development (I'd need to see sources about the Nintendo line) but we are well into it so the struggle is pairing down to fit a certain resolution.