The other thing to consider is the used car market is hot at the moment, so depending on the trade-in situation, for some it may be beneficial to buy now at MSRP rather than buy at a discount but lose value on the trade.
Shift.com paid me about $3,000 more for my trade than I was expecting, plus I made it in just under the wire for a $2, 000 state rebate, and the day before the 1.85% financing expired. Getting a 1st Edition at roughly a $2,000 discount vs. a similarly speced Pro Gradient also factored in.
So while I'd love to have negotiated a deal on the purchase, taking the time to do so may have cost me more overall.