I'm sorry, but that's not a very good argument.

First of all, if it didn't matter, why not simply store the passwords plaintext? I'm sure I don't need to explain why that's a bad idea.

Also, we all know that users like to reuse passwords. So, let's assume a system that has to automatically create networks and users on the firewall. For this, it requires an API key (with admin privileges, because of the user creation).

If this system is compromised, the adversary can (obviously) modify arbitrary settings in the firewall and gain access to other parts of the network, which is bad enough.

But instead of telling your customers "Hey, we messed up and an attacker temporarily gained access to some parts of the network (s)he wasn't supposed to.", it's "Hey, we messed up and an attacker temporarily gained access to some parts of the network (s)he wasn't supposed to. Also, all passwords were stolen and if your users aren't very security-minded people, all your confidential business information that was stored in mails etc. has now been stolen.". Alternatively, the passwords may be used to gain further access to (now accessible) systems.

Also, all passwords are unsalted (not that it matters when using md4).

I'm asking you to seriously reconsider this decision.