The Ike and Luigi changes are very natural; they really aren't that big of a violation of anything. Also, yeah, we don't really plan our responses here out so we might occasionally goof up in what we say. If anything is pressing, we'll confer together and give a more solid "official" response.
Also, we are aware that not every matchup can be 50-50 (if such a thing is even desirable). However, we feel that, less a few game changers which are really extraordinarily tame to have such a title (they change a major part of those characters' games or add extremely significant new options, but even with them, none of the characters really "feel" that different), we can get everyone pretty close to evenly balanced. My personal point at which I could be really satisfied would be the point at which every character could, used ALONE (not with secondaries), win a major tournament (90+ people). Due to a limit of the number of top players not every character might actually do it, but character should not be a wholly preventive factor. That would definitely still leave room for character superiority; it just means being the game's worst character and being a bad character don't have to be the same thing, more like "overall still virtuous but just in a lesser way than some others".
Balance doesn't declare itself anyway, and we figure we'll know we have something good when no one can any longer agree on a tier list. We believe it to be possible, and we believe our initial release to have been true to our general principles of not changing the core principles of Brawl. There is some inevitable change in the sense that "if you change things, things will be different". However, I feel as though we have made a quality product without violating our principles, and I reject as false the dichotomy between balance and our principles.
As per general matchup ratios, my ideal would be everything in the range of 60-40 to 40-60. That's a lot of wiggle room, and given that we expect a web of matchups and not just "good character tends to go 60-40 while bad character goes 40-60", it could even be healthiest in the end.