Hi, good question.
Tasers in America are not used just for an 'alternative to a gun, they are used to pacify someone when they are 'resisiting arrest - basically a form of punishment.
They can also be used if an officer feels 'threatened'.
This is known in the design industry as 'product slip' - because the original design brief was to be in a lethal situation (to the cop). This is also known as fooling the American public who believe the taser would only be used in a life/death situation.
7 people sitting on a man (un armed) and unable to move is not a lethal situation, yet cops still use tasers. Incredible.
The problem is (as you correctly stated) the man you refer to at John Kerry's speech speaking, well he is being held down, he is thus incapable of 'resisting arrest' he is also not able to threaten anyone.
Like you, I find the fact someone is tortured when they resist arrest quite wrong, but Americans do not. There are no mass protests in the streets - Americans are used to violence.
When 30+ students are murdered at Virginia Tech, was anything done about restricting guns? No. There is no empathy left.
If citizens face this overwhelming force by their police on a daily basis, they they grow tired and apathetic to evoke change - exactly the position the Government want.
See the video of the student (Famous UCLA incident) being tasered for not getting out of his chair at a college library. People yell at them to stop, they are threated too.
Why? The answer is plain simple. Power. If it was legal, the cops would shoot them all dead. Electrocution is one step away from death, and they electrocute all they wish. No body cares, nothing is done.
Or read the news today, a woman tasered to death in the USA (10 taser shots) - she was in a wheelchair.
http://news.yahoo.com/s/wkmg/20070919/lo_wkmg/14147512
Or the 11 year old tasered in a school (yesterday).
http://www.wsbtv.com/news/10424467/detail.html
See the video of a black man (surprise surprise) again tasered to death. His crime? Nothing. He did nothing, the police grabbed him, tied him to a chair and murdered him - because? Because he was terrified they were going to murder him. Since when was being scared of being killed, a green light for Police to go kill people? America did nothing about that also.
Tasers have killed 200+ people in the USA so far, and soon they are coming to Britain because they are 'safe'.
America is sadly a fascist state, and executes more people a year than Russia.
Russia is meant to be their enemy. ''Communists''. When Bush preaches freedom and executes more people in his own country, in self proclaimed 'best nation on earth' then something is wrong.
Don't blame Americans, they are brainwashed by corporate media news networks like 'Fox News' which is run by Bush's brother.
Americans are nice people, but sadly unable to control their neo con Government who seeks total world domination - starting that domination over their own citizens.
Have a look at the video clips I've listed.........and don't forget that 1 in 5 Americans are on mind altering medication (Including cops)...
No surprise that a 'taser' becomes the equivalent of being told off then, is it.....
Peace.