You should only implement a feature if you really need it. Less features will mean less code, and therefore you reduce the possibility of bugs and security issues. Only give admins the capabilities they really need, because of the principle of least privilege: if the admin account gets compromised, less privileges will mean less possible damage.
Most CMSs (Content Management Systems, like WordPress, Joomla, etc.) have several roles with different privileges, for example: guest, user, editor, vendor, administrator, super administrator, etc. The most privileged accounts are able to change almost everything, including first and last names, contact info, and passwords. Being able to change names, addresses, etc. is very useful in some cases, so that's probably a feature you will need. On the other hand, I'm not so sure about the need to change users' passwords. Technically it introduces the possibility of promoting some bad practices (like setting a password and then sending it via email or other insecure channels). However I don't think it's a real security issue either, because changing a user's password is probably not the worst thing a compromised admin account would be able to do. In all the CMSs I've seen, an admin can actually install software at will (plugins and extensions), so I wouldn't worry about the ability of changing users' password, generally speaking. In your specific case though, if you don't need this feature and you can avoid implementing it, do avoid it.