Personally, I don't think school uniforms are a bad idea aside from when it involves mandatory skirts for girls or when the uniforms are ludicrously expensive... But I also have an obsession with uniforms so I'm totally biased.
Also, cool dictators have cool uniforms. Evil bastards are always cooler when they make everyone dress snappy!
Also, a proportion of any given population is stupid enough to follow anything they deem attractive and forgive all its flaws... Like Edward Cullen and any villain that gets Draco in Leather Pants treatment.
But the one argument against uniforms that always pissed me the hell off is "MY KID CAN'T EXPRESS THEMSELVES IN UNIFORMS!"
Apparently you have a child who is incapable of human speech, is a talentless hack who cannot do anything of interest, and has no personality outside of wearing products that commercials and peer pressure tell him to buy. GREAT KIDS.
Because rarely are the people who cite self-expression talking about shirts their kid personally made, it's always some raunchy shirt they bought or those stupid rubber band bracelets that schools think are the workings of Satan (but for some esoteric reason, never ban rubber bands) or whatever "scandalous" thing is popular at the moment with them young whippersnappers.
Though I can totally support going against the more insipid things schools have gone against. Like when kids get suspended because nail clippers are clearly part of some nefarious terrorist plot or when schools have rules against "gang colors" but then "gang color" gets defined as something nebulous like ANY SHADE OR AMOUNT OF RED. GANGS CAN'T OWN RED. It's even more baffling when the school's mascot color is... red... O_o HOW DOES THAT WORK?! Though McDonald's says it owns red and yellow (and the name McDonald) and will sue your ass over it. T-Mobile also thinks it owns magenta and will also sue your ass over that magenta square.
...this is why lawyers will all be shot when I'm a dictator.