It's not an installer problem, meaning the installer is not very smart and doesn't accept future versions of P3D. The problem is, the installer does that check, because every new release of the product will require we update the Addon Manager too to support it, because there are some things Simconnect still doesn't provide, so we need to look for them directly in memory, so every new build will require a new Addon Manager so, if the installer didn't stopped you, the Addon Manager would refused to run anyway, otherwise the program would very likely crash.
So, in order to use the P3D 1.3, we need to update the Addon Manager too. It's not a difficult tasks, but it might still take some days. My P3D 1.3 installer is still downloading now as we speak...
It's no different for FSX, we still have to support a specific version, so in FSX we support only SP2 and Acceleration, but after those builds, it wasn't updated in 5 years so, nobody really uses RTM or SP1 anymore.