I was gonna avoid this thread because personal brand choices will be blamed for user's opinions, but here goes.
-Yes, they are cheap to produce. It is impossible to deny that this has to be at least partially the cause of the cord wrap choice by the manufacturers.
-Yes, they can be replaced. Whether because of wear or to change the 550 for something more personal (paracord comes in some pretty cool patterns now). Think about it: hot pink on a little neck knife makes it cute instead of tactical. Not that I'd want a pink knife, but that's another story...
But being easily replaced is a bonus, not the feature that sells them.
HOWEVER, if you actually USE knives that have properly done cord wraps, they are trully appreciated. No safe queens at my house. All my current fixed blades (plus my 3 HAKs) have 550 wrap. When you squeeze the handle tightly, your skin or glove squish into the cord pattern and is locked into place. Very secure. When I use a tool, I want performance above anything else. I don't care how much a sawzall vibrates its way through exhaust, as long as it cuts it easily. Same thing with knives. Give me performance over comfort (they aren't that bad...unless you're the kind of person that moisturizes). Sure other materials can be secure and more comfortable, but they rely mostly on handle shape. Paracord wrap will outgrip grippy G10 anyday. If you dissagree, you haven't used a cord wrapped knife.