I’ve seen a lot of stories about lazy cops and security who pull out the taser as the first, rather than the last, response. That’s bad police and security work.
Having said that, if the cops are faced with someone who won’t calm down or respond to requests to surrender or stop, they shouldn’t have to put their lives at risk by continuing to ask nicely. If you are told to calm down and you continue to mouth off and act belligerent, don’t be surprised if you get smacked or tasered or roughed up.
Even if the drunk decides to get physical, it's still the case that (1) he's not at the top of his game in terms of agility, and (2) he's vastly outnumbered.
A taser is a hi-tech cattle prod for cops who don't want to get their hands dirty and nothing more.