The general idea is naturally that laptops have pretty long battery life now and that people will use them less and less being plugged in most of the time. In a sense like people rarely use iPads plugged in to power. Of course, besides battery life, something you carry around a lot (like an iPad) is less suited to being used while plugged in. The difference with a laptop is still that you'd likely use it while sitting somewhere (so you can easily use the keyboard), and if that somewhere is a desk, a constantly plugged in charging cable is less of a hassle and much more likely to be plugged in even if you could get all day battery life. Then again, the lighter and smaller the laptop is, the more likely you are to carry it around in house and while on the move, and thus the less likely you are to have it plugged in a lot.
So, there is some justification to leave out the MagSafe port on your lightest and smallest laptop. There is sense in the general direction they are moving but one naturally disagree about the particulars.
