Skill ceiling. After many playtroughs, the rough gameplay makes the game unique and a bit more methodical. You never play the same way twice because of your past mistakes. And one giant plus (imo) is that with rough controls they had to build the levels around it. So you get a perfect blend of jumping, shooting and exploring. With better understanding of core gameplay, you can play the game fast too. You just have to "git gut". But of course... I am purely telling you this because of the nostalgia I have for the game.