I forgot to answer all the things in this. I kinda said my opinion on how balanced DOA is.
1) Is doa not considered a tournament fighter because of how unbalanced it is? Not really. I think personally, the people prefer street fighter, tekken, injustice and so on is one of the big reasons. Idk about the past DOA's but there's no "World tour" or "Cup" or "Pro Series" that keeps me off my seat for a tourney. I think DOA's biggest tourney's NEC but anyone can register for it. Fan service is 50-50. It hurts the reputation only because people look at female's fighting in bikini's or whatever costume and they look at it in a negative fashion, but in most media industries: sex sells.
Now to the balance thing. I kinda said my opinion but I'll re-iterate. I feel DOA's balance is similar to Tekken's. Not all the way but it's comparable. I say this because although there's no barrier to what characters can and cannot win (Lucky Chloe goes far for being "really awful" and Bass has make some top 8's I think), there are styles that seem preferred in a tournament setting. Tekken I feel prefers whiff punishment, "game-breaking crushes" as Aris would say, evasion, defense, pokes, counter-hits, & low-mid level execution, which is why Jack does really well despite being a mediocre character and Aris talks highly of Lili in tournaments. DOA I feel prefers speed, counter-hit, good stun, evasion, defense, versatility & likely low-mid-level execution, which is why this year, Rachel's been more relevant. Not to say Akira or Hwoarang can't win but there's a reason why those characters are seen but not as often as Christie or Dragunov.
2) You have characters like ayane who have literally every advantage. Ayane is a pest but not for the reason you explained. I kinda think that up close she's easier to handle since she kinda has a tough time opening you up if you have firm defense. Up close she has to get good counter hits in order for her to truly be dangerous. However, where she excels is her spacing and close-in moves. Like I said she wants a good counter hit. If you're rushing in trying to hit a button her stuns can catch you and her close in moves are a pain to handle but you have to stay firm. But then again, I lose to Ayane's pretty often online so, maybe my advice isn't the best.
3) Than you have characters like jann Lee who is almost all 1s 2s and 3s for stats. Now 1st, I'd disregard the stat thing. It's not like Injustice or anything, if injustice stats matter (I don't play it often so Idk). Jann's solid. Similar to Ayane, he's better as a spacing character. His close game's alright as he does have some decent tools but he's better in the mid-long range game. His throws do little damage somewhat but his dragon gunner's pretty effective (So long as you don't spam it) as it's a good reset for pressure situations and it leaves you at advantage making your opponent have to guess. Jann's a solid character. If not for his frames and such I feel he'd be really great for a tourney scenario.
4) Fan service: I kinda touched on it so I'm not saying that one again.
5) New characters:
Mai: I kinda said this on Mai but I mind as well re-iterate, Mai online (Along with many other characters) is a huge pain to deal with. No if's and's or but's about it. However when we really dissect Mai, She's another character that highly needs counter-hit to truly dominate. She's not like Kasumi where Kasumi excels at rushdown in addition to getting some decent counter hits. Mai has some close in tools & evasion tools and I'll say she's high tier to me. However, if you're well grounded, Mai will have a hard time fighting you.
Raidou: Well I'll leave that for someone else to talk about. The only Raidou I play's DBomb. I'll say this, he's very hard to use since he's slow and his execution level's pretty high for someone who's pretty slow and fundamentally sound. Unless you're fighting EDK or DBomb, I wouldn't worry much about Raidou. He's rarely seen anyways.
Marie Rose: Marie is a pain for me as she's someone with good holds and tools that seem "game-breaking". However, the more you fight her, the more you'll understand. She relies, to me, on two things: 1) good counter hit & 2) catching a good hold. She makes you aware to pay attention to your detail as well as hers. However, at least she doesn't have shoulders like Leifang. But I guess her hop's enough of a pain to deal with. I'd pay attention to her and you'll be fine.
I might be 100% wrong about all of these but I'm basing it off my experiences online & offline.
6) What is DOA doing?
Only Master & Tom Lee knows. I speculate that they're working on DOA 6 and this new character for DOA x3 but that's my speculation.
7) Even out the characters?
Give Rig Hayate's 1k or Handstand or shoulders and I consider everything even. All jokes aside, I feel that new characters & styles should be introduced. And improvement's with gameplay will help to even out characters. Not really buffing & nerfing characters.
8) Half the roster not used?
Not because they lose to Ayane, Marie Rose. Heck I don't even know if Ayane's been relevant in a tourney since Ghp and same with Marie Rose where only SonicFox excels. They're not used to me because either they're boring or they don't fit their tournament criteria. I can't use certain characters because they don't fit my tournament style that'll help me win. I feel that's the same for everyone else. Plus you have to factor execution and other factors which is why even Ayane & Marie Rose aren't in tourney's often. You don't get away with errors offline like online. Risk-reward plays huge. I'm not gonna risk a game with a character no one see's if it's someone, I know I'ma lose with in a ft2.
Lastly,
Marie Rose a character for pedophiles:
Kinda goes with the fan service thing I said.