The fact that names 'date' is not rubbish. When did you last meet a baby Dudley, Trevor, Kevin, Patricia, Barbara or Maureen?
Nothing wrong with those names, but our generation isn't exactly rushing to use them for their offspring - because they're dated to our ears. We may not necessarily use the word dated, we might think 'old-fashioned', 'middle-aged, 'frumpy', 'tired', 'dull', 'boring',* etc, etc. But the outcome is the same. The names are eschewed because they're not current, and have negative (not bad) associations.
I'm also not saying this is a reason for not picking a name you love. But like it or not, there are people out there who don't want their child to have a popular name for this exact reason. It sounds nice now, but won't forever. And when there are so many lovely names out there, it is very tempting to go for one that has more of a timeless, less-used quality about it.
*Disclaimer: I don't necessarily think these names are any of the adjectives I've listed, and can definitely see how some of them will be re-claimed in another generation or so, because they'll sound fresh to their ears. :)