Bikes have been made with wheels ranging from about size 16 to size 70 inches. Today, in the USA, most wheels use tires sized at about 20 inches, 24 inches, 26 inches, and 27 inches.
But, without doubt, 28 inch tires have been the best seller. Around 1900, Raleigh began making the DL-1 with 28 inch tires. Until around 1970, that model, and its clones, were best sellers both and in the USA. That British three-speed bike that Americans called "an English Racer".
And, today, in India and Africa, hundreds of millions of people contine to ride the DL-1. Available new in India for around $50. Available new in the USA from "Yellow Jersey" for around $300.
From a pure "theory" point of view, twenty inch wheels are the best. A BMX wheel with 48 spokes, and wide, beefy 20 inch rim ain't NEVER going out of true. People ride these wheels off a twenty foot high roof, and land on concrete - neither their "IQ", nor the rim has gotten any smaller. Both are quite small, before, and after.
Dahon builds folding bikes for folks were are NBA height using these wheels. They can fold-up small enough to put your bike in a suitcase or in a backpack. Bents using these wheels would leave Lance in their dust.
But, sheep are sheep. Mountain bikes will continue to use 26 inch tires. Road bikes will use 27 inch/700c whees. Logic has nothing to do with how people spend their money.