What would the install all button do? you watch a resource like a macro or a Lua, and it gets put in the launcher then you hit the button to install it, and thats it, then you can keep all your resources updated with the update all button.
remember plugins dont need to be watched, they are allready in your install, and gets updated it they need to be when mq gets updated.
the only plugins that will appear in your plugins tab is the premium pay plugins, and they appear without watching the resource one you purchased access to them.
and will get updated too with the updates of mq.
Do you mean a button to install all the luas, all the macros?