The short answer is Banks do not like it.
Builders rely on their line of credit from banks to run their business. If they can not sell their new houses, bank will not release new fund for them. That will be the end of their games. Also the high rate of construction loan also make it impossible to rent.
Why do Starbucks, Wal-Mart rent instead of own their own building? Again, bank/wall street do not like it. It will make their financial statement not as strong as if they rent. Their finance cost will be much higher.
