Possible solution for the World Championship match: always playing a tie-break before the classical phase.
In case, the main phase (12 classical games) is not drawn, the tie-break will be of no importance for selecting the world champion. Simply, the winner of the classical phase is always declared the world champion. Only if classical phase ends in a draw (6.0 – 6.0), the – previously played – tie-break is decisive.
The key idea is that a tie-break loser will have stronger incentives to play aggressively (offensively) than now. Already before the first classical game, he will be certain that without winning at least a single game out of 12, it is impossible for him to become the champion.
The incentives would be the strongest in the 12th game if after the 11 games the result is 5.5 – 5.5. To have championship chances, the tie-breaker loser will have to risk playing for a win.
The idea described here is a direct analogy to the solution proposed in the literature for soccer (see References below).
Carrillo, J. D. (2007). Penalty shoot-outs: Before or after extra-time? Journal of Sports Economics, 8, 505-518. (link)
Lenten, Liam JA, Jan Libich, and Petr Stehlík. "Policy Timing and Footballers' Incentives: Penalties Before or After Extra Time?." Journal of Sports Economics 14.6 (2013): 629-655. (link)