Let me guess... you also advocate storing your money under your mattress because investing it in an interest bearing account or stocks would be lazy. Scholarships and grants for college? No way! That's lazy. Earn your way through college by doing some menial job for less than minimum wage.
I'm going to stick my neck out here and say that people who use mules just to get fast credits are playing VMK in a smart way. Creating a character and using it just once yields a very high return on that investment. The very smart ones do little things like remember to choose a hat for the character because that means five more credits when you sell the clothes. I believe the saying is, "Work smarter not harder."
That said, I admit to being somewhere in the middle. My goal isn't to be one of the richest characters in VMK but I do want to be part of the upper middle class. I have a lot of characters but I use them to play games and such in order to continue to earn credits. I have never just gotten credits and then abandonned the character. However, I don't have a problem at all with people doing that and I don't think they should be banned. VMK can easily recycle abandonned characters.