With that, we have a large part of why Apple has abandoned the show. Ten or twelve years ago, Apple needed such a high-profile event to get its products noticed by as many people as possible. Additionally, they'd pack as much into those precious 90 minutes as they could, while they had everyone's attention.
Today, that's not the case. Phil Schiller noted that 3.4 million customers visit their retail stores per week, worldwide. The "lesser" press events, like the annual September iPod announcement, attract all the attention Apple needs. These are much less expensive to produce and allow Apple to release products when they're ready, not when the calendar reads "January." Therefore, there's no cache of goodies waiting for the Moscone Center, which always disappoints Wall Street and adversely affects Apple's stock price.
Sure, it's sad to see Apple go, but the "why" is clear.