This is most likely a bug if the non resource power plants, or hives can receive adjacency bonuses from other buildings. I'm not talking about the capital that seems to work, like, before it would make sense on a island. Unlike before it works fine connected to the capital. Playing almost solely as the for I actually don't know if hives, and non resource power plants don't do the same.
If the power matrix doesn't receive adjacencies from the factories, research facilities, or wealth improvements that it is connected to. Yet let's say factories which they both have plus one bonuses do. Then if you want to take advantage of adjacencies then you wouldn't use the power matrix.