> being different (read "weird") isn't always better!
To go further, being different is almost always a bad idea. People are used to how current stuff works; you need a really good reason not to provide the same interface.
Sure, now, but was that the case 10 years ago? I'm not arguing its the best choice but more that you need to take into account the age of things. Being exposed to it just now doesn't mean it was created in that situation. I'd say 10 years ago rpm based distributions were the more dominant and emulating rpm was a fine choice.
It is weird mostly due to exposure to other tools. IIRC nix started out over 10 years ago, well before apt or yum became very widely used.