I was a carpet installer/repairman for eighteen years. My motto on my card was “If I can’t fix it, it’s time for new.” The proof of a Master installer is knowing the right thing to do, the wrong thing to do and when to do them. A good install is all about ascetics while maintaining a good installation. If you have any questions about installation you may contact me and I will give you the answers.
And the answer to this question is, if you want the carpet to last more that a year or two you must stretch the carpet or it will wrinkle or wear badly in the traffic areas of the room. Also remember the foundation of a good installation is just that, the foundation. Good padding is as important, if not more, than the carpet you buy!