Every laptop in existence, up until quite recently, used a proprietary power connector. The fact that Surface also uses it as a dock connector doesn't erase thi

Every laptop in existence, up until quite recently, used a proprietary power connector. The fact that Surface also uses it as a dock connector doesn't erase this fact. But it does point to the fact that many of us have such a dock, and are very happy to not have to buy a new one to use with our new Surface Pros. It also won't hurt that our old power adapters should still work. One particular gamble of the Surface line was that it relies on accessories to really meet your needs. Microsoft has done a commendable job in this area, allowing me to "upgrade" my Surface Pro 3 with a new keyboard and pen, and now allowing me to continue using all my accessories with the latest device. I agree they have to break compatibility at some point, but I don't think there's much value yet in doing so. Maybe in a year or so, USB-C will be standardized and reliable enough to really make it advantageous to use as a power supply for all my devices. But it's not there yet.