That's a fair point. Though I'd point out that two of the three pre-Thunderbolt (which—and I assume you know this, but I'm adding it in for the casual reader who might not know—uses the USB-C connector) Magsafe cables actually used the same connector, so you could use them interchangeably. They just improved the way the cable itself worked to come out at an angle instead of 90º. And that the new post-Thunderbolt Magsafe laptops can also be charged using the Thunderbolt/USB-C ports, so it's only adding a new option, not replacing one.

So it's definitely worse than their mobile devices, but not quite as bad as it might at first seem.