Here's my take on the motivation:

My LM Wave cost me @$70 new. It is handy as heck for all the other things besides the knife blades. Still, the knife blades are the primary use of the tool without a backup blade, and if something happens to the knife blades, then I have to do without the whole bloody thing when I send it in to get repaired (the same could be true of any other tool on the Wave I suspect, but none so critical to my everyday use).

So for most of my actual cutting work, I like to carry around a little $7.00 Ka Bar folder. If I break it, I still have the wave for backup, and I can go down to the corner store and pick up another cheap replacement without much inconvenience on my part.

So I guess the convenience of having a multi-tool at hand is offset some by the inconvenience of breaking a piece on it and having to send the whole thing in or (gulp) buying another one. I don't see much point in owning two when all I need is just the blade, so there you have it.