I have read that u shouldn't wake a sleeping baby, but after birth the nurses pretty much make u wake and feed them. Why? What should u say to them?

Let the Baby Sleep. I believe that babies are hardwired to wake up for feedings when hungry, when they are full term. As others mentioned, there are fads regarding feeding that seem to, at times, ignore nature. Do not worry, but consult your pediatrician for advice.
Let baby sleep. Baby care undergoes periods of theory based upon the current fad. This may include rigid scheduling in which the baby gets needs irregardless of sleep/wake cycle. It may include cuddling, swaddling, certain feeding habits, etc. All seem to do well regardless. It is best to discuss this with your pediatrician.