I have always replaced both sides as a matter of course, but I am not suggesting that everyone does what I say, The OP asked for advice, I gave him my advice, Thats me, belt and braces.
My advice is free, if people don't want to take advice from me or you the sobeit.
With tyres, I was referring to certain cars that don't like having one tyre replaced, yes, I agree, not every car but some.
I don't see that a bearing of such small value is a waste of money, you would have peace of mind, and lets say, you only change one, and the noise is still there, what are you going to do? Eh, replace the other one. If the noise is gone problem solved, if the noise remains, well, something else is at fault.
Not everyone is adept in diagnosing problems/faults, we all have our own method of doing things, what I have posted is my method.
Paragraph near the bottom of the page.
http://mibearings.com/