Triplanes shouldn't be interception masters, they're triplanes. Air power is an area where the force projection is so strong, and especially potentially strong with humans, that a bit of randomness helps keep that projection from being a guaranteed plow-over. I feel that the slight obscurity of air combat, especially early air combat, is a fair trade-off for the power and force projection it allows.
I feel like in this situation we have not explored alternatives, but moved right into random intercepts. Again, I am fine making interception do less damage if we think at base its too strong. We can weaken certain Air promotions, like the one that auto heals every round. Maybe planes don't benefit from medic, etc.
In the previous model I may have agreed with you that air power was too strong because Triplanes did it all. They stopped other planes and killed units, and do "ok" against cities. Now triplanes exist as pure anti-air, with pretty limited ground attacks compared to bombers. You effectively need 2 planes to do the same job as one...that's a pretty large nerf.
So in summary, I agree with you about the potential power of planes, and agree with you that its important to ensure a reasonable curtailing of air power in the spirit of balance. But I believe we can explore several other viable options that don't introduce a random element into an otherwise non-random combat system.