What's so wrong about adult kids at home?

Now this maybe a touchy subject for some but it is worth discussing. People freak out when they hear that adult kids are still staying at home. What is so wrong with it? If you have given birth to them and nurture them till they grow, how come we want them not to stay at home for a bit longer. Nowadays with the economy in the doldrums, adult kids need more help than ever with their own finances and it is perfectly all right to come back to their parents. Where else do you suggest they should stay? Less job prospects, crushing student loans and other financial hardships makes it imperative that they should stay with their folks until they save enough money to be on their own. On the other hand, people say that if the adult kids come back home, then they will not able to stand on their own, housing market and the economy will suffer. But if you can mutually help each other in their hour of need there is no harm in staying together. I believe that parents will never shun their kids and say that don’t come back. In fact they welcome their adult kids with open arms. But as the kids are adults and parents will be parents, there need to be set rules and boundaries so that there is no clash of values between the parents and kids. I believe adults kids being at home after college is beneficial for both parties in the long run as kids save on rent and having the loving parents to talk to and the parents enjoy the company of their kids no matter what their age.