Most people can't pull them off, but that's true with lots of things.
I think it also depends on what you mean by "skinny". The standard, at least in US, seems to be bootcut or baggy jeans, at least among the general population. A skinny jean, to me, are those horrible torture pants you sometimes see kids on skateboards wearing; I'm aware, however, that, to some people, a skinny jean is anything that flatters the figure.
For me, I prefer a slimmer, straight cut. Skinny jeans - the super-tight variety - scream youthfulness and rebellion; they stand out, they make a statement, and it's not a very subtle one. For some people, that's fine - that's what they want, or what they like. They can pull it off. But, I don't think most people can.