In one word, RECOIL.
A 28 gauge will do almost everything a 20 gauge will and won't punish your shoulder.
Generally, a scaled 28 gauge will be lighter and is a joy to carry.
The science of recoil math is very simple. Recoil is controlled by weight of gun and shotload, and the velocity of the load. You cannot shoot the same shotload at the same velocity in a lighter gun without greater felt recoil.
It is possible to shoot lighter shootloads and lower velocities and still have excellent results.
I have picked and shouldered numerous 28 and 410's in gunshops and on clay courses. They are the grass that is greener on the other side of the hill.
I too dreamed of a sweet lightweight 28, but the more I searched the more I discovered it was difficult to find a 28 than was not heavier than the lightweight 20 gauge guns I was finding. Taking into account the shorter shot string of a 20 vs 28, it makes best sense to me to reduce payload to 3/4 and skip the 28 gauge altogether.
I tried hard to pick one gauge (16) and only one, but even though I use it 90% of the time, i have not been able to avoid other gauges
I believe like the 16 the 28 appeals because it is different.
