Well yeah, but that goes for any character. "If people just learned how to DI shine, smash DI dair and u air, and learned not to shield grab Fox's pressure it would make the matchup that much easier." In both cases, the character cannot be boiled down to just a few moves. This is only the perception you have of Snake because so many people
don't have the matchup experience. I've been playing the character since 3.0 and I still wreck people I've played with weekly since that time. There's a lot more to the character than just depending on inexperience.
Also: I'm willing to bet what you see as "running into stray mines" is actually " getting pressured into stray mines because it's been forced to seem like the best option." A big (HUGE) portion of the Snake gameplan is actually just limiting options to force your opponent to make a wrong step—and I mean that quite literally, since mines are Snake's best KO move in 3.5 against everybody except fastfallers, and it's made exponentially better if you have a C4 as well. Tranq is the same way: I only ever use it in a tech chase situation where I know the opponent won't roll the other way (like when I have a mine set to that side): if it's timed correctly, tranq covers both the tech in place and the tech roll. Again, it's not as simple as "shield tranq."
I frankly never use f-tilt, so I can't speak much on that note, but what happens when they mix up with its second hitbox? You're offstage because you were too busy trying to tech it.
Shield grenade honestly is a bad habit that Snake mains get into because it's easier than timing the roll/spotdodge. But the spotdodge grenade is SOOOO GOOD because you don't get any of the shieldstun while your opponent (if they shield) does, which nets a free grab. So what happens when you try for the grab and they're really just baiting you with a spotdodge? You eat a grenade and they're free to combo you for 50% into a C4 stick/KO.

My point is that characters are never robotic in their actions: they always have an opportunity to mix things up on you, and if you're not respectful of that, you're gonna eat a huge punish.
It's not well established yet that Snake is a hugely technical character. It's no coincidence that the best Snake main right now (Prof Pro) is a melee fox main. It's also not well established yet that Snake players need a fantastic understanding of what advantages they have mentally over the opponent. Playing Snake requires a player to be 100% on point in both the micro- and macro-game: in both the inputs they perform and the general spacing game. Prof exercises both of these aspects at a high level, so it's no surprise his Snake performs so strongly. Snake is the most richly deep character of the cast, I think. That's why this is a stupid thread.
However, to answer your question: DAIR. DAir is so good. First three hits act as jabs, and you can mix up the number with a fastfall, while the third hit sets up for (depending on percent and character): any aerial you want, utilt, usmash, C4, or grab. I'll uthrow dair C4 people, and they tend to shield instinctively, so I'll just grab them and repeat it, or just chain grab into U-tilt C4 KO.
ALSO: Utilt is the best launcher in Snake's arsenal. It's about as strong as sweetspot up air, and has more mobility and far less startup than down smash (which otherwise is the strongest launcher). It has comparable horizontal reach to the grounded C4, comes out two frames faster than grab, has comparable vertical range, AND sets up for the KO earlier, which means that it's actually the most optimal punish for tranq hit confirms, and most other situations where you're looking to launch an opponent. For example: Marth dies to U-throw C4 combo at 81% before the grab on FD in 3.5. Marth will die to U-tilt C4 at 70% given the same parameters. Working utilt into your Snake game is really really important because Snake in general likes being below his opponents, given his Cypher, Grenades, Uair, U Smash, up tilt, and C4 all work fantastically in those situations.