Because their approach to design is completely unique. Their industrial design studio is small, insular and incredibly secretive. That studio has almost complete independence; most Apple employees won't see a new product until the design is finalised and ready for launch. They have an overt belief in the wisdom of ignoring user feedback and media criticism, going back to the original Macintosh. They don't think that their role is to provide people with what they want, but what they should want.
That approach is one of Apple's greatest assets. They were right to ignore the people who said that a computer needed serial ports and a floppy disk drive. They were right to ignore the people who said that a phone needed buttons. They're willing to ignore conventional wisdom and the demands of the market in favour of a singular design vision for what technology should be. They're willing to tell their customers trust us, this is for the best. That approach is necessary if you're going to be a highly innovative company that creates entire new categories of product, but it's not right 100% of the time and it can be infuriatingly stubborn.
The strain relief on the MagSafe connector was too short. Any cable manufacturer would tell you that it was too short. Any electrical engineer would tell you that it was too short. The internet was full of pictures of frayed (and sometimes charred) MagSafe cables. The Apple store website was full of one-star reviews for MagSafe power adaptors that had frayed. Apple did nothing for over five years until a class action forced their hand; they offered replacements, but didn't fix the defect.