I mean there's nothing saying you can't have a break-away cable even now. Look at the Xbox, the controllers are USB and they break near the system if the cable is tripped on. It's perfectly possible to have USB type C and MagSafe at the same time.
In fact, you could probably have a USB-C-to-MagSafe-to-USB-C adapter. Knock your laptop and the cable comes loose, with the adapter left plugged into the port.
Battery life is long enough such that MagSafe isn't as necessary as it used to be. Back when you had to haul your power cord to meetings, coffeeshops, and the like, cord tripping was a serious problem. Now? Far less so.
Have kids and/or pets run around in the same area where your computer is plugged in. Sooner or later one is going to tear on the cord - heck, even I do manage from time to time. And the connector looks so flimsy I'm afraid one time is all it's going to take. Nah, macsafe was the best invention ever in terms of charging.
so I have a reduced chance of incident occurrence, but if it does, it's probably fatal vs. a high chance of non-fatal incident. Bad trade if you ask me.
Judging by the coffee shop I'm in at the moment where about 1/3 of people have their machines plugged in, I don't think plugs are dead yet (not to mention at home or in offices, of course). Part of the problem is that the battery life is not yet at the level of phones. My 11" 2015 Macbook Air advertises a battery life of "up to" 9 hours web-browsing or 10 watching videos, but in practice I've found it closer to 6-7 while working actively, if I've got several apps open, wifi on, and screen brightness up. Maybe switching from Firefox to Safari would help, dunno (but I'm pretty tied to Firefox at the moment). I can get 10+ hrs on planes, but there I have the screen brightness turned down, wifi off, and am mostly working in a terminal vim.
Counter-point: As not-the-primary-computer, my MBA is plugged in 80% of the time and gets moved from place to place as my crowded workspace dictates. I can't count the number of times I've accidentally yanked the Magsafe connector out trying to move it just out of cable reach because I needed to get at something underneath.
Granted, a lot of that is learned behavior because I know I can yank the Magsafe out without incurring a $500 repair.
I leave my laptop on the charger as much as possible to avoid cycles on the batteries. And even if the charger is connected for 5 minutes the possibility of it getting yanked out is present. The lighter the attached platform is the worse the risk, since without the breakaway connector you can yank the whole laptop onto the floor.
Couldn't you simply build an adapter to get that magnetic ability? I'm envisioning a standard connector to laptop, bit of cord, proprietary connector with built-in magnetics but maintaing USB 3.1 compliance out to a female USB-C connector.
If USB-C becomes the go-to port for charging, I can't imagine something like this not being far behind.
Considering the new MacBook is just 2 pounds, I guess they'd have to put a really weak magnet in there to actually keep your Mac safe. I assume the threshold where the plug should "let go" is pretty close to the force required to keep the cable plugged during regular use.
Related: Can you still open the lid with one finger without lifting the bottom case up with it?
I think I'd have to say it's worth it for full standards-compliance, though.