No you’re getting it wrong: you LOSE sensitivity because the head of your penis is getting direct stimulation all the time. Because of the resultant loss of sensitivity the expectation would be that you would take longer to finish.
But sex is a complex thing that involves a lot more than just the physical stimulation, so it’s not 1:1 with regards to speed. It IS howeve impactful for the pleasure of the person with the penis. It’s more intense and pleasurable for people that aren’t circumcised. Sex is obviously still great even if you are circumcised but it’s a little like being colorblind if you were circumcised at birth: you don’t really know what you’re missing so it’s kind of ok and not really bothersome for the majority.