I'd be willing to bank the number one reason they switched it is because the Apple logo on the laptop is a selling tool. It's a small piece of branding thats prime purpose is selling more laptops to potential buyers. It's not meant to reinforce the brand to someone who has already bought the laptop, there are hundreds of other things that are already doing that embedded in the operating system and throughout the user experience.

With the current orientation of the Apple logo, every time someone opens their laptop, they've essentially set up a little billboard advertising Apple for everyone in their near vicinity to see. It's even backlit to draw attention. Before the logogram was oriented this way, it was a poor advertisement and I'm sure some marketers in a big board room argued it worked against brand clarity.

Seems like a no brainer for Apple to switch it to its current state.

Personally, I dislike being a billboard for products—so brave, I know—but even if I do think they have a fantastic product, I've already paid a shit-ton for their services, and I'd appreciate not being included in their marketing campaign without being asked to. I'm not going to say, "Apple, how dare you make a billboard out of a product I bought from you," because I recognize that's an unfortunate part of competitive business today; however, I do think it would be a well-received risk for them to remove the Apple logo entirely from the back of the laptop—their laptop design standing on its own is already a very recognizable product—but the cynic in me doesn't see that ever happening.

Anyway, sorry for the coffee rant. Simple solution: cover Apple logo with sticker.