That's awesome for the developers!

Well, yes, it is technically rendering twice as many pixels, and this will obviously use some of the additional processing power the PS4 Pro has (otherwise they'd just do the same on regular PS4s) . But this is just a bit disingenous to say "converting a game to Pro is just 0.2% or 0.3% of overall efforts". Yes it can be that simple, but that is a bare minimum effort.

My point being is that this process can be optimized, and there will additional resources left over that can be used to enhance the game further. It is those further enhancements that I am referring to. And if you think every modern game engine is easily scalable, I'd go poke under the hood of Uncharted 4's engine. I bet you many of Naughty Dog's "to the metal" enhancements they did to get more out of the PS4 hardware aren't going to scale so easily without adding bloat to the engine, and fundamentally making the game run worse (even if it is only very minor). Optimizing game engines isn't trivial on consoles. Those that do have a mastery of it have some of the highest paying jobs on video game development teams because the skillset and technical know how is extensive.

It's always nice when producers do their best to make their HW easier to program.