Depends, I suppose, on whether or not the memory capacity of the human brain is effectively finite. If it is, then you can argue that some less directly-relevant things could be 'useless' by taking up space that more-directly useful things could use.

That said, AFAIK, no-one in psychology's ever suggested that anyone they've studied has actually run out of memory space. So whatever the capacity of the human brain actually is, it's sufficiently enormous not to be a practical problem.