For me, first and foremost, the hammer provides a visual and tactile indication if the gun is cocked, or not.
It gives you options that do not exist on a striker fired gun. How important those options are, to you, is a personal matter, but having them allows you choices that not having them does not.
Mechanical safeties can, and sometimes do fail. Hammer down is ALWAYS hammer down.
Tap, rack, bang is the tactical drill, and the only thing you can do with a striker fired pistol if the round fails to fire. With a hammer gun, you have the option of a second strike. (it may not matter, but at least you have the option)
I like having options...
The only "hammerless" pistols I have are Lugers, some .22s and an XP-100,