This objection doesn't make any sense. The status quo is that if you tug on a Lightning cable, your phone will be tugged along with it, and will likely fall off the surface it is on. If you make it a MagSafe connector with appropriately weak holding force, and do the same thing, your phone will be tugged less hard, and will thus have less of a chance to fall off the surface it is on. It can't help but be an improvement, even if it's not a perfect solution.
The objection that actually does make sense is to point out that Lightning is a) reversible and b) has 8 separate data contacts on each side. It's not just a power connector. Can't really duplicate this with MagSafe or anything similar.
However, if you tug on it, there is a chance that it will not disconnect with a Lightning cable. There's still a good amount of force needed to actually pull and disconnect the cable. This means that if you, say, trip and fall, there's still a chance the cable will still be connected and limits the amount of distance the phone will travel.
With a Magsafe-like cable, it'll disconnect after the tugging happens, and if the pull from the tug is strong enough, it'll cause it to potentially go a greater distance, since there's no cable connected.
The objection that actually does make sense is to point out that Lightning is a) reversible and b) has 8 separate data contacts on each side. It's not just a power connector. Can't really duplicate this with MagSafe or anything similar.