The biggest misunderstanding of game balance is that it’s a) easily controlled, and b) it’s about everybody being equal.
In reality, this is the worst case scenario. Technically SF1 is a perfectly balanced game since there’s only two characters to play and they’re exactly the same. But nobody ever praises this level of game balance. Why? It’s boring. Having everything be perfectly equal is boring. Even Chess, which is almost perfectly balanced, isn’t taking the world by storm. Why? It’s boring. It’s essentially the same matchup, a lot of the basic strategies have been fleshed out, and it all comes down to execution. Only top level players or geniuses are able to develop anything new or innovative nowadays.
So really, what you want is a tight compression of tiers in a competitive sense. You want to eliminate seemingly unwinnable matchups, while keeping each character’s design in mind, but make it fun enough to create variety in balance. This is what people like. People like the idea that certain characters and matchups have their strong points and weak points. It’s fun fighting a tough matchup, but you don’t want the matchup so imbalanced that it’s oppressive.
A 7-3 matchup isn’t really all that bad in the scheme of things. A 30% win ratio is enough to pull through in a 2/3 set, and with enough player skill, a 3/5 set. It gets problematic when matches start to be pegged at 8-2 or 9-1. Fortunately, these really don’t exist in SF4, and even if they do, player skill is the ultimate determination of how your match will go. Tiers are extremely subjective and based on known variables that can’t possibly exist in the real world. There is no such thing as two players with absolutely equal skill. At the end of the day, one dude will always put in more work than the other guy.
While Capcom does their best to balance out these matches, all they can do is try. Even the most minor change to a character can completely shift their tier positioning in drastic ways, which is why they tend to do extremely minor tweaks and changes to their characters. I don’t even think their goal is to make the game better balanced. From a business perspective, they just want to reinvigorate the game with changes in order to maintain playerbase interest and prolong it’s competitive lifespan, they really don’t give two shits to game balance, that’s just a nice side effect.