Revenue wise, the services part is not that large. Profit-wise, though, I don't believe the same is true. Their 30% cut is barely costing them anything compared to manufacturing hardware and physical logistics.

I don't think the Mac App Store is going to get to iPhone levels of lock-down soon, but Apple thinks in ecosystems, not just in laptops. If you have an iMac, you probably have an iPhone, and you're probably going to buy an iPad should you ever want a tablet.

If they wanted, they could open source all of the drivers necessary to boot an OS as part of their Darwin core, but they choose not to. That actually breaks with their older, more open development style. I guess they just don't see the benefit of being open any longer.