It was a practice designed for the days of non radio aircraft and poor navigation equiptment.
Well, since neither radio nor any kind of navigation equipment is required for VFR flight it is as relevant as ever, right?
Surely it must be a good idea to agree on one location for joining the pattern? Early on downwind (as in an overhead join) is the ideal location since it is usually where the workload is lowest. This gives the best chance of avoiding someone else who is joining and hasn't seen you! The fair number of turns required in the overhead join maximizes the opportunity for relative motion between the different aircraft, making it easier to spot each other. If you are on downwind and someone is joining on base, with no relative motion, you could have a very hard time spotting them, especially if for some reason they are slightly lower or if visibility is not great. I'd rather not be totally reliant on
them seeing
me.
Furthermore, the procedures used must cater for the lost comms scenario, even if "everyone" usually has radio. A procedure based on "I give 'em a call, listen to replies and join wherever I want based on what I hear" does not allow that. Let's also recall that in many lost comms situations the pilot is not aware they are lost comms (mistuned radio, audiopanel incorrectly set etc), so the ideal procedure should be robust in such a situation.
When there is no ATC or AFIS I usually consider it prudent to have a good look at the airfield from above, noting any obstructions, activities and of course the windsock before joining the pattern. From that location, surely the overhead join is the most straightforward procedure to use? Running out a long distance and descend far outside the pattern on the live side to join 45 deg on downwind seems awkward.
The only thing I see as potentially unsafe about the overhead join is when multiple aircraft arrive simultaneously from different directions, as those aircraft could have trouble spotting each other (no relative motion). A slight dogleg about a mile or so before arriving overhead should be helpful in ensuring relative motion before or after the turn.
But I am not sure what is the best procedure to join if low clouds prevent an overhead join... Run-and-break, perhaps?
I'm at loss as to why ATC would ever require anyone to perform an overhead join! I have never come across a controlled airport where ATC does not provide sequencing to join the traffic pattern; then again, I never fly in the UK...