The question is, how is it better? When you have something that works, replacing it with something that's just not worse is unnecessary churn and work for everyone. It shouldn't be replaced unless its replacement is somehow better.
> It also supports newer functionality like net namespaces, and uses newer kernel interfaces.
Why couldn't these have just been added to ifconfig? Surely it could have been ported to the new kernel interfaces. As for features like net namespaces, the syntax should have been added in a backwards-compatible way instead of rewriting it all.