I've pretty much no-lifed this game since it came out and I've only played Frost. The TLDR here is that I strongly disagree with you, and consider her a very solid character as long as you're willing to adjust expectations and put in the work. She isn't potato and she's far from buddying up to anyone in MKX but as far as this version of the game stands I think she's good. That's subject to change as the game is still so new, but for now here's why I think your points are incorrect. Keep in mind that everything I'm about to say applies to her Ice Machine variation, as I haven't played Frost-Byte and don't intend to.
1. "Her lack of OH..." You deleted this, as you should have, but I'll take a second regardless because people have been saying this about soo many characters. You do not need an overhead starter to win a game. You do not need an overhead starter to be viable. Especially in a game that has universal overheads.
2. "Her punish damage output sucks" This is an actual weakness, but characters have weaknesses. Sometimes we have to punish with a D2 or Lunge when other characters get a full combo. Her punishes can be weird and DO require lab time. But it's okay. You're not meant to be a dangerous punishing character. Lab the punishes you're having trouble with. Also, as someone else pointed out, we get F2 man. It's a damn fullscreen AA and excellent whiff punishing tool. Frost has nutty whiff punish potential in general.
3. "Her Krushing Blows blow" I disagree strongly with this. You have a KB off of whiff-punishing something with your best string and Ice Machine has an easy KB after landing three MB Lunges, which you'll do in most games because the move is a combo ender and an effective whiff-punishing tool. She also gets TWO throw KBs. Meaning after your opponent fails to tech a throw, the next one is a 50/50 and they're losing big life if they guess wrong. Also D2 KB which is universal but still counts. Her Krushing Blows are fine especially when you compare them to some other cast members. This complaint just comes off as whiny.
4. "S1 and S3 range" They are very stubby normals. Frost has plenty of stubby normals. This is on you though. If you're getting bodied because you're whiffing strings that's entirely the fault of the player, especially if it's because you "read that the opponent is going to press buttons" like c'mon man. It would be great if these buttons were longer but it's not the character's fault you're just using them at the wrong times. It sucks but we just have to adjust.
5. "Her damage output midscreen sucks" This is another whiny complaint man. Play a high-damaging character then? Most combos are 300+ for a bar and her enders give her excellent corner carry or a hard knockdown. It'd be a little wild if a character with Frost's kit could hit for 400 MIDSCREEN. Relaaax friend.
6. "What's her style?" She's a space-control monster with incredible counter-zoning and one of the best projectiles in the game in Ice Machine's DB2. Most of her options are safe. Moving against her is incredibly dangerous. Everyone's gonna play her differently but that's an excellent foundation. Build off of that. Sorry she's not as easy to classify as 'zoner' or 'rushdown' but that's what makes her so fun.
7. "No good AA options" This is just wrong. S1, Ji1, S4 and D2 are all good anti-airs for different situations. She can easily convert off of most of her AAs too. I'm not saying she has the best AAs in the game but they're solid. Not a weakness at all imo.
The character does have flaws. She's far from perfect. Her pokes are ass (though they do have good range so we have that going for us) and its hard for her to stop some characters from mashing all over our shiny bits. Her up-close punish game is weak. Her mids leave a lot to be desired. Her post-D1 game is ass. But she still has so much going for her. F2 is crazy. Auger Lunge has great range and carries the opponent like crazy. DF2 is completely safe. Max range B2xxDB2B is actually nuts and some characters can't do a thing about it. Her counter-zoning is super effective. Her Fatal Blow is SO GOOD. Again, just adjust your expectations. Stop thinking of the things you want and start building an effective gameplan around all the things you have. To answer your question, yes, I think Frost is completely viable, especially if you have a secondary that can cover some of her more unfavorable match-ups.