Given you can get cheap adequate armoured gear I personally think its crazy to contemplate a trip without it.
Many would argue the opposite but at 80 km per hour a trip down the road has the potential to gouge out some serious layers of skin.
Then you have the same issue you have with a burn, potentially large areas susceptible to infection.
Depending on where you are in the world you may have less than sterile options for treatment. A bad case of Infected road rash will end your trip just as quickly as a broken leg.
If for whatever reason you don't want to wear armoured gear you can get something like the Draggin Jeans Rider jacket which is kevlar lined and looks like a casual jacket.
Having said that there is a guy on a Honda 110 something or other who has ridden around the world mostly in shorts, t-shirt and flip flops.
So I guess it comes down to what level of risk you feel comfortable with.
I have seen enough accidents on the job to know that for me that means ATGATT. YMMV