Binary is a local maximum in terms of entropy vs complexity. Going from one state per element to two states per element is an increase from 0 to 1 bits: an ∞% increase. Going from two to three states increases it to 1.585 bits per element, or a 59% increase.
Cheeky math aside, getting signalling logic to work with ternary, especially when clock rates go so high the signal starts to look less like square wave pulses and almost more like a modulated sine (due to slew), you now need much more sophisticated decoders.
Yes and / but you now have "long distance" cross-chip busses where driving and receiving from that internal network is part of the cost of doing business.
Cheeky math aside, getting signalling logic to work with ternary, especially when clock rates go so high the signal starts to look less like square wave pulses and almost more like a modulated sine (due to slew), you now need much more sophisticated decoders.