I would be all up for playing the final with an even number of games until one player has won more. If it takes 20 games, it's going to be legendary. 8)
And I wouldn't mind that also in earlier rounds, although I understand that you want to have some upper bound.
But I don't see how playing an 8th game only after a draw is fairer than the current rules. If you could choose to go first and have to win, or to go second and a draw suffices, who would want to go second?
With an odd number of games, one person will have to go first more often than the other. Ideally, you want the choice of first player in the last game to not affect the win probabilities ex ante. Having the rule that a 3.5-3.5 is enough for the second player makes this choice a bit less relevant.
And I wouldn't mind that also in earlier rounds, although I understand that you want to have some upper bound.
But I don't see how playing an 8th game only after a draw is fairer than the current rules. If you could choose to go first and have to win, or to go second and a draw suffices, who would want to go second?
With an odd number of games, one person will have to go first more often than the other. Ideally, you want the choice of first player in the last game to not affect the win probabilities ex ante. Having the rule that a 3.5-3.5 is enough for the second player makes this choice a bit less relevant.