Consumer preferences differ widely. Universally, however, most consumers care little for 'fastest 80-120 times' etc.
...which car is easy to drive, cheap, and gives me good value (and reputation for quality). That's the equation that has helped the Civic and Corolla move so many units.
Mazda has sought to appeal to the driving enjoyment at the expense of outward visibility, polarizing style, and a volume package that is a bit more expensive than its competitors. Often I hear, "well, if I can get a Mazda3 for $20,200, why would I choose that over a Corolla for $19,500?" You've got to be priced at or below the benchmark and appeal to what consumers actually want.
The Corolla's LED headlights are universally praised - a brilliant move by Toyota. The Civic having a backup camera and heated seats in the LX trim? Conservative and smart move. Kia/Hyundai are doing very well with their value propositions as well. Mazda offers better driving dynamics...*cricket cricket*
If I were to replace my Corolla, I'd get another one or an Impreza (for its AWD). The Civic is too expensive to insure and has harsh suspension, and the Mazda3 is narrow (tight interior dimensions) and feels cheap to me.
Mazda appeals very well to those who objectively view car sales. Unfortunately for sales numbers, most consumers purchase based on subjective desires, not which car is the 'best'...objectively.