Ah, another perfect pilot enters our midst.
By your "logic"
Pilots don't need EGPWS . . . we have altimeters and navs for positional awareness.
Pilots don't need gear warning horns . . . we have checklist.
Pilots don't need TCAS . . . . for that is the job of equally infallible ATC.
Pilots don't need runway incursion warning systems or hold short lighting at busy airports. . . .for we have paint on the pavement.
Pilots don't need Windshear warning systems . . . for we have weather reports and airspeed indicators.
Pilots don't need stall warning systems and shakers . . . for pilots would never fly below Vs 1.3.
Pilots don't need overspeed indicators . . . for we would never exceed a flap speed for VMO thanks to our airspeed indicators.
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Unfortunately though, all pilots aren't 100% "perfect" as you. So thank you very, much, but I'll take all the help I can get when it comes to catching stupid mistakes.
(but you can of course ignore all those warning systems when you're flying . . .. after all, YOU would never make a mistake, and if they ever activated you no doubt have a broken warning system)