Let me first say that this is a neutral post from me. I'm not on either side. With that said, I wonder how often robberies actually happen and how they compare to any similar sized city anywhere else. I see it mentioned over and over here but have only seen reference to the incident with the unfortunate murder in Puerto Madero over the watch.
What I do know is that these types of unfortunate events happen a lot in big cities in the US. It's just that it only makes international news when it's someone from a first world country having trouble in a third world country.
The only crime here that I would say is definitely higher here than in a place like the US or a European country, is phone theft. I'll admit that here your probably 50x more likely to get your phone snatched if it is just sitting on a table openly.
I've been here 3.5 months and have witnessed 1 attempted crime that didn't go well. A father and his very young son were a tag team snatch and run group. The child tried to snatch a phone that was sitting on the table of an outdoor restaurant. The kid didn't make it 5 feet before someone stopped him. The father tried to step in but was taken down by another person. They kept the father pinned down until the police arrived. The surprising thing was that part of the crowd wanted leniency for them.
I myself wear a watch valued at around 2500. I wear it most of the time. Although it's not as common to see really high end watches like in a big US city, don't think that it's completely foreign. There are store here to buy Rolex, Hublot, Audemars, etc. Louis Vuitton, Bally, Hermes, etc also have clothing stores here. The streets are full of BMWs and Mercedes, although owners have to pay double. Don't think that there is no money in BA. You will here a lot more about people who only have a little to survive on, than the fact that tons of restaurants in Palermo, Recoleta, Retiro, y Puerto Madero are packed every night.. and in those restaurants you're not going to eat for 500 pesos.
Bottom line is that you only need to come and enjoy yourself. If you're wearing a 300 dollar watch, there is a 99 percent chance that no one gives a shit.