Because arbitrarily penalizing businesses during an emergency incentivizes businesses to move to locations which don't do this. Texas tries to be friendly to business and it seems to be working.
Do you really want power company bureaucrats curating a clipboard of businesses deemed non-essential?
As opposed to what? The way we do it now is we deem certain business essential, and by default, everything else isn't. All power companies have a plan to ration and route power in an emergency.