As far as balance, this game is very balanced. Having so many ranges in characters is a good thing. If you want everyone to be 5/5 or just have two levels of characters, then this game would be boring as hell. The only game that I can think of which has the most balance is Virtua Fighter. How many people play Virtua Fighter for all the balance that it has?
Hey, man, VF is my game!
Its funny you say that because Soul Calibur is in the same position as VF5 -- It was pretty big when it first came out but now its in a position where only the core players are left. The reason its not big anymore isn't because its balanced (that's actually a term of respect every fg community knows VF for), its because other games drew its fans away, ironically starting with SC4. VF is just a 'later-term' example of SC4's position right now, where most of the players who left are waiting for a new installment.
As far as the High tier characters go, to all the high tier players, the problem isn't the fact that their high tier. At least to me it isn't. The problem comes in to the fact that with CERTAIN high tier characters, it takes pretty much NO EFFORT to win matches.
For example, I believe that Cervy, Setsuka, and Seigfried are all high tier. Nobody has a problem with them, or even if they do, its not enough of a problem to become vocal like for Hilde and Algol. Their all high tier, so what's the problem?
With the first three, you HAVE to put time, effort, and study to be able to pull out wins, let alone win tournaments. With Algol and Hilde, all you need to do is exploit bubble infinites, or instant Ring Out combos to immediately be able to win a stupidly high number of matches. It doesn't take long to learn those two characters, all you need to know is a couple of combos. And you could argue that many Hilde players don't really 'know' Hilde because you don't see them use the rest of her moveset, besides a few DOOM setups.
Whether or not Hilde or Algol win tournaments is not the point, the point is that the players that wield them are able to have an extremely effective advantage before the match even starts, while lower ranking characters (not even necessarily low-tier characters) have to put in an extremely high amount of hours of practice, study, and playing to counteract this.
Winning in any fighting game SHOULD be about skill, but its simply not the case with Algol/Hilde. What skill is shown about Algol winning from a bubble juggle? There is some, but what is it compared to winning with Talim or Taki? If anything, its a slap in the face to the low or mid-tier or even high-tier character player, because dozens of hours of practice can be negated by some weak, instant RO shenanigans. Its a very economical decision to pick Hilde/Algol, because it doesn't take much effort to get instant W's, and I'm not mad at anyone who does, more power to you. But it simply goes against the spirit of what FGs should be about, which will scare fans away easily, because some people simply wont put up with it and flock to another game (can't really blame them).