'One baggers', at least those who post online about it, are very consumerist in general despite the practice being about minimalism.
You'll find people posting about upgrading their bag from the $300 Aer Travel Pack, to the $400 Goruck GR2 because of style preference. I've seen someone talking about repurchasing items they already own in a particular color to match their packs color scheme.
I think the motivation for many has nothing to do with being anti-consumerist and more about just freedom to travel without paying-for/carrying-around checked-in luggage and all the other benefits of travelling light, which is fine.