Maybe all characters aren't built to be used based around their fastest mids?
Uh, which character's gameplan isn't based around their fastest safe mids? Let me list some off the top for you so you can see that mids DEFINE characters in this game:
Frost: b2 range is where she should be. It's her go to string, it's safe, you can stagger it, it's got long range, it's got a little mix. The rest of her kit is there to SUPPORT b2 mixes
Kotal: F2 is his best string by far, the next is f3 a forward advancing low with good range. Those 2 strings DEFINE his game plan. Everything else he has supports putting him at a range where he can use these strings. F1 is used only for whiff punishing.
Shao Kahn- F4, B4, F34- he alternates between grabs sweeps, f3 staggers and punishing with s1 for the majority of his gameplan. You might never use any other strings in neutral for the rest of the match. F2 will get you rocked by people who know to neutral duck at that range.
Jaqui- need i say more. Once she gets in it's 9f mids and a long game of "is it my turn yet"
Liu Kang: the current reigning champion of "is it my turn yet" with f4 being his most used string and the base of his gameplan
Scorpion- f3, teleport- a neutral destroying mid or a safe stagger mid to mix with grab. Scorpion has other nice mids too but these are pretty much all he needs.
Kung Lao- f4 or grab. You've seen Foxy play. It's safe mid or grab. Anything else is risky as hell.
I'm not gonna discuss Erron, Sub, Geras, or Cassie. These should be obvious.
Damn near every character in this game has a tool kit the supports their mid game not the other way around. The way you can test that is that if you remove any character's MAIN mid string they instantly become F-tier. And by MAIN mid i mean a mid that is relatively fast which can somehow be made safe or is staggerable.