Not so many fires in a building are going to be electrical fires. If they feel they will have electrical fires then they could add a second type of suppression system for that, but a building needs sprinklers.
Besides, while the origin could be electrical the fire itself may be onto conventional combustibles. So once the fire was big, a sprinkler would have helped. The only thing is when water gets on live electrical stuff there might be the chance of electrocution but most of the time nothing happens. Just stay away from the electrical thing. You'd have to be up to your ankles in standing water where there is also a live device of very high potential. Simply getting wet does not make bare live wires or busbars any more lethal than they already are. That applies in the sense we are used to, like a fire in an electrical room(and they all have sprinklers btw) or when your teakettle wire frays and starts burning the paper towels. I could pour water on that and it won't do anything such as make the fire spread or anything disastrous. Water starves the fire of one or more of - oxygen and fuel and heat. but a KERS thing is a different story. even if it is the origin, there's a conventional fire now, but there might not be anything electrical present anymore. And another besides, besides the other besides
, water is actually a good insulator. It's the impurities that make it a conductor. You can fill a styrofoam cup with tap water, which isn't even clean btw, clip 2 alligator clips with 120VAC between them on its rim so they are immersed, and safely put your finger in the water.
Andrew mentioned what I was afraid to: that no one, except those trained and assigned to, should really have done anything at all. Yes their bravery is admirable but if I did that at work and got injured, and a few did, as I am trying to get Workmen's Comp they would ask me what the he77 I was doing fighting a fire. I'm an electrician not an emergency response technician. I could get in trouble.
There used to be Halon here but it was found to be an ozone depleter. Any of these FM200 or CO2 ones need the room to be shut and occupants egressed first.