There is no direct problem and this is more of a preference but I'd like to have an option that blocks every single command in the server for the regular player. Then admins can use a command like /allow to allow certain commands.
So it pretty much turns the whole plugin around. When by default most commands are allowed and you can block them one by one, then you could allow them one by one.

This would give the server more of a mainstream feel because all different plugins have their own "permissions denied" message and this way there would be one error message for them all. Many plugins also have many little features that many don't want and feel useless and with this feature those would be gone by default and you can only have what you want.

This option would also likely prevent exploits, backdoors and other loopholes (by default) created by plugins.