Ever watched a film on television, and it's apparent that it was made a few years ago? For some reason, unless you're into old films or you like re-runs, it's somehow not as enjoyable to watch.
Often you're not even sure why. It's just the look of things that you can't necessarily put your hand on.
Nowadays a dated website is also one that's not mobile friendly. So important is this aspect that Google even provides a tool for you to check your own website.
A dated website looks unloved, out-of-date and tired. Old fashioned, even, and slow to change.
If that's how you want your club to be presented, that's fine ... but don't expect to attract new or young members. You don't fit into their view of the modern world, and they won't fit into yours.