Legend of Zelda is worse with...

Hello everyone, and welcome to this month's issue of "Everything's Worse With...". It's so great to see how many of you out there still resist the lure of the "Rule of Cool" as an excuse to screw with movies, games and TV shows. 

Today, we'll be looking at Legend of Zelda and why it's fine just the way it is.




DINOSAURS!
Yeah, why not introduce a dinosaur into the ecosystem of a world that never even had something similar? Just one Brachiosaurus, for example, would be enough to mess up, say, the Lost Woods.
And don't get me started on the carnivores! They would greatly alter the food chain, with catastrophic, unpredictable consequences. Take the Hyrule Field for an example, before and after the introduction of Velociraptor:

Fig. 1: Simplified food web, detailing the relation of various  species native to Hyrule Field

Here you have the normal situation, or at least a rough approximation of it.
Lizalfos are armored and show some degree of intelligence – Bokoblins hardly are competition for them.
Perhaps the only danger to them is the Baba Serpent. Its ability to detach itself from its roots means it has a much greater range than a basic Deku Baba. It also enables the Serpent to attack enemies from behind easier – thus letting them exploit the weak spots of Lizalfos and Helmasaurs. In turn, it might be preyed upon by the Kargaroc, which is capable of flight and shows some evidence of intelligence, and can attack from above.
The Helmasaur's heavy armor is most likely an adaptation to attacks from the front, which makes its unarmored backside an easy target for Lizalfos, Baba Serpents, and Stalhounds.
Stalhounds are nocturnal and hunt in pairs – perhaps a male-female pair, perhaps some other structure, if you're hunted by them, you don't have time to lift their tails and look. In any case, the pairs are an excellent strategy to fight Helmasaurs – one distracts it from the front while the other one attacks from behind. With that degree of coordination, it is even possible that they might hunt Bokoblins.
And now, after the introduction of Velociraptor to the area:

Fig. 2: Simplified food chain, showing the situation after the introduction of Velociraptor

In essence, Velociraptor eats everything except for the Kargarocs, which it can't reach normally. In order to survive, Kargarocs have to change their behavior and become scavengers, eating what Velociraptor leaves behind.
But of course, that doesn't matter to people who think, "Boy, a raptor in Zelda sure would look awesome!". Those people just slap together something, five minutes in Photoshop and bang! there you have it – a raptor in Hyrule Fields. And because it looks cool, they, they post it and package it and slap it on a T-shirt with a "funny" caption, and then they're selling it, they want to sell it-1 … but I'm ranting again. Sorry. 
ZOMBIES!
Oh, you mean these?

Fig. 3: The Common Hyrulean Zombie, Zombie hyruliensis

Didn't think so. But the real ones, as you know, wouldn't be too impressive, either. I'll just leave the explaining to the fellows over at Cracked.com.



VAMPIRES!
In Zelda games without a day/night cycle, those would have serious problems.



ROBOTS!
In a fantasy game?



ALIENS!
Now that would prove a serious problem. What we have here is a pre-spaceflight civilization. Aliens land there. Now one of two things could happen. Firstly, the aliens have peaceful intentions. They teach the Hylians all about spaceflight. So now you have a ton of warriors and whatnot suddenly able to fly into space, without having to work for it, without having time to mature. That's... probably bad.
Secondly, the aliens could be hostile. With the Hylians having slingshots, maybe, and swords, they wouldn't be able to put up much resistance. That's... certainly bad.


PIRATES!
Well, Wind Waker wasn't exactly the most popular game in the series.... (though to be perfectly fair, depending on who you ask, so was the original. And A Link to the Past. And Link's Awakening. And Ocarina of Time. And Majora's Mask. And Oracle of Seasons/Ages. And Four Swords (Adventures). And The Minish Cap. And Twilight Princess. And Phantom Hourglass. And Spirit Tracks. And Skyward Sword. ... Did I forget any?)


[1]: Crichton, M., Spielberg, S. (1993): Jurassic Park.