GCN clearly never commuted all year round, all hours of the day, all weathers.
Performance wasn't of interest to me. Security of the foot-pedal interface was.
I used to teach this professionally, and have a few views of my own...
1. You will fall over at some point when something unexpected happens, especially when tired
2. Stopping and starting on hills is particularily hazardous
Most such "moments" are attributable to a rider with insufficiently developed skills and coordination. I have
never fallen over while clipped in and I put my trousers on one leg at a time like everyone else.
3. Because the cleats are relatively small the shoes need stiff soles which can result in 'hotspot' on your foot
That can be true, but isn't universally so. For example, I have never suffered hotspot issues regardless of the shoe. In any event, stiff soled shoes are easily available so it's a non problem.
4. Clipless limits foot movement - makes it difficult to change your foot position to relieve your knees,
Not an issue if the bike has been set up in an orthopaedically correct manner to begin with.
5. Clipping in and out in stop/start traffic is not only a right PITA but dangerous - I have seen plenty of riders having to look down because of failing to clip in instead of concentrating on the traffic
See my answer to points 1 and 2 above. If yourre having to look at your feet your fundamental skills aren't there to begin with.
6. Unclipping can involve a significant angular rotation of your foot which isn't ideal for longevity of joints
There can be some truth in this. Careful pedal adjustment and cleat selection are crucial to avoid this, and most riders suffer zero issues after decades of spd use.
Some people simply dont like clipless, and I totally dig that. However, most of these "reasons" against are lame at best.