WhiteFangofWhoa said:
Rule of Cool aside...
Conventional nukes are launched from ICBM silos. Metal Gears and the Shagohod are silos on legs. With the right computer hardware, it would be possible to predict a launch trajectory and fire with a much wider and less predictable range than a stationary silo is capable of. Also harder to destroy with jets or your own nukes since they can just move out of the way.
I don't believe the nuclear stuff came into it until the Solid series. The original Metal Gear games just had it as an ultra-powerful walking tank with lots of varied weapons. No idea if it is actually possible to fire a nuke from a giant rail gun without its own propulsion trail. Probably not, but see above.
The original Metal Gear actually does mention "Nuclear Armed" during the one or two times it talks about the titular mecha. The big pros that Metal Gear has going for it are:
-In MGS3, Granin goes on about it being "The link between infantry and artillery" that can presumably traverse any terrain with the power of heavy artillery. The manual for MG2 details the idea of using heavy lift helicopters to transport it around if need be, and MGS3 actually showed this in action(as ridiculous as the idea of using like 6 Hinds is).
-Harder to track. It's about as trackable as a tank but that's a lot smaller and a lot more mobile then a missle silo.
-The Heavy armor and weapons means it can hold it's own in a fight(most artillery isn't particularly good at close range fighting, if not completely useless). Well, allegedly, since Snake took out 3 of the things on foot(that we know about) and Big Boss did just as well.
-Has a Crew of 1(except for the ones that were autonomous, like Peace Walker, ZEKE and snuffleupagus), which is a hell of a lot less then a submarine that requires like 100 specially trained crew.
-Presumably does not require special maintenance and repair facilities like a submarine does, though we never really saw what it needed as far as support goes. It probably has a much smaller logistics tail then a submarine does(Don't get me wrong, tanks are logistics and maintenance nightmares but submarines are much more specialized).
-You can hide it in an underground hanger when not deployed, which is shown plenty of times in the series. In fact, the first time a Metal Gear is shown in the series it's just sitting in its hanger which isn't terribly huge.
The big downside is that other then Rex, it's hard to see how any of them had much range. Pretty much all of them had basically a missle pod attached which limits the size of the missile and thus the effective range. Even the Shagohod wouldn't have had nearly the range it's claimed to have(even if you could get a tank to go that fast without flying apart or crashing into something, the boost in velocity wouldn't give it any noticeable range increase over a stationary launcher). Metal Gear would essentially be a heavily armored tactical nuclear platform.
Incidently, this type of thing does/did exist in real life. The term is Short ranged/theater ballastic missles, nuclear weapons designed with a range of about 100 miles or so. However, they're normally launched from what's essentially a military semi-truck because they're still pretty big. Almost none of the metal gears shown in the games(except maybe Peace Walker, because Peace Walker was fucking huge) look like they carry a big enough missle to actually reach that far. REX, due to the rail gun, is probably the exception, because it presumably doesn't need a missle to deliver the warhead across vast distances. THe rest of the the metal gears look like they'd pretty much be able to fire a nuke a couple of miles and that would be it.
And of course, RAY doesn't count due to being a hunter-killer of Metal Gears, not a nuclear weapons platform and Arsenal Gear is a damn submarine (I'm surprised the US Navy didn't just name it the USS Metal Gear).
In real life nobody actually has been able to build a decent bipedal vehicle that's worth the money and trouble to do so. Getting the legs to work properly so the thing can carry it's own weight is a major issue(Peace Walker points out that Huey was the one who solved that problem, which is why he's essentially the one who built it, as opposed to the Russian Officer in Snake Eater who came up with the concept) and there's also the matter of being able to power it. And other concerns such as the tall profile which makes it a larger target.
Of course, the real explanation is that it's Japanese, and the Japanese seem to be obsessed with giant robots. That and Kojima finds it a good shorthand to discuss his feelings on nuclear proliferation/deterrence when he's not being batshit insane.
It's just something to accept if you're going to get into the series.
