"A minimalist lifestyle does not make you a better person. But it may make you happier."
I would argue that if you're a happier person, you are a better person. So if a minimalist lifestyle makes you happier, a minimalist lifestyle makes you better.
Seems like an odd article to me.
EDIT: Seems like I'm getting flack for about "what if the person is evil but happy, are they a better person?..."
Apologies for not explaining my argument well the first time. The author argues that being minimalist makes him happier, less worrisome, less irritable, and have less liabilities, but not a better person. If being minimalist makes you all those things, then I think it does make you a better person than if you weren't minimalist.