Solid Hardwood, Engineered and Laminate Flooring - Question about Flooring nailers

Why are most of flooring nailers actuated by hammer?
I think pneumatic nailers actuated by trigger is easier and more save labour than nailers with hammer.

Flooring nailers/staplers use specific nails/staples for the job, set at the precise angle of attack. Actuating them with a hammer tends to tighten up the joint simply by the force you are exerting on the nailer foot. You can buy pneumatic as well as manual flooring nailers. Of course pneumatic nailers work considerably better, but cost more. Pneumatic finish nailers are used to start your first two rows by nailing in the tongue as you indicated, but you switch to the flooring nailer and continue until you reach the third row from the end. That row will be nailed with a finish nailer through the tongue. The last two rows will be face nailed above the edge of the tongue. I use a minwax color coded scratch pencil to fill the holes and hide them.
Bottom line, the flooring nailer will be a must. You can rent them or buy them. Rent will be about $30 a day.