It's not just the charger wire. I have a clear example of Apple prioritizing form over function in the charger itself:
In 2011, my wife and I bought new laptops (a MacBook Pro and a ThinkPad) around the same time - based on the same Intel chipset and with similar CPUs (might have been one speed tier apart). The setup was power-hungry, so my ThinkPad came with a proverbial charging brick - big and bulky, but it kept the laptop fed no matter what. Her MacBook came with a standard Mac charger (much smaller and lighter). But if she used her laptop when plugged in, it didn't charge much (if at all). And if she did something particularly demanding, the battery could even drain (fortunately, she didn't do that too frequently).
This seemed odd and I remember coming across an explanation online (while researching something else): It was just physics. My ThinkPad charger was something like twice as powerful as her MacBook charger, but they were both feeding roughly similar internals. Given that Lenovo concluded my ThinkPad needed the more powerful charger, it's not at all surprising her weaker MacBook charger couldn't keep up with her laptop.
On any list of functional requirements for a charger, I'd say "not letting the battery drain while plugged in" has to be pretty high on the list, so...