If you value the status symbol of a Rolex (not I - I think they are tacky and ugly - sorry) fakes diminish that both for the producer and consumer. As another said, they also introduce the chance of fraud by intention or mistake.
That said, I think overall fakes provide excellent advertising for the real thing and probably increase profits. Anything widely faked implies the real thing must be valuable.
Fakes are only a problem if they're falsely advertised. If something says "Rolex" but it is not, then that's a major problem. This is why trademark laws exist. But if something looks like a Rolex but says something other than "Rolex" on it, that's fine.
Samsung has never done anything remotely like appropriating Apple's trademarks, so it's all rather silly. There's huge difference between a knock-off and an outright fake.
That said, I think overall fakes provide excellent advertising for the real thing and probably increase profits. Anything widely faked implies the real thing must be valuable.