It is still possible to have realistic boss fights. Nathan can encounter more high tech adversaries that have Helicopters, amphibious vehicles, and other mechanical things that can be transformed into boss fights. And ND has one of the most creative directors in videogame history, so I'm sure she could have easily come up with better ideas than me.
The destructable environments, platforming, seamless gunplay, intiuitive control scheme, and lush environments would make supreme combination to make some of the most enjoyable battles ever witnessed in an entertainment medium.
It is one thing when they omit a feature that isn't needed, but when you see a game engine that has nothing but infinite possibilities against larger than life enemies I can't help but look at all the wasted potential.