Discount codes for many shows on a short term basis -- they want to sell these tickets so that they can justify selling more.
If 500 people are going to use the discount code (just a random number) they'd rather those tix help full up the theater now, in the next month to six weeks, then those same five hundred being spread thin over six months, say.
As the deadline to the current code comes close, another will be offered -- which doesn't help your timing.
Of course, the hope will be they will have a HIT on their hands and can abolish all discounts. (Like Book of Mormon, for example.) From the sound of it, that won't be the case here.
If we're not having fun, then why are we doing it?
These are DISCUSSION boards, not mutual admiration boards. Discussion only occurs when we are willing to hear what others are thinking, regardless of whether it is alignment to our own thoughts.