I agree too - you make a good point. Walking fluidly would go a long way towards making taller heels acceptable in an office environment. That said, not many people do and fewer still would care to wear 120mm stilettos all day, but would keep those for evenings and nights out, and stick to more easily worn 100mm stilettos - assuming they were high heel lovers to start with.
Others, those who wear heels grudgingly, as an obligation, will stick with lower heights and will probably be the ones casting censorious eyes at colleagues in towering stilettos - setting up the informal, unspoken rules about appropriate heel heights.