Foot retention is overrated -- for me. I use it on my road bikes -- toe clips in ye olden dayes of yore, clipless now -- but not on my hybrids. Looking at my data over the past few years, there's little correlation between my best performances and foot retention. My fastest times on my 1993 Trek 5900 OCLV were still set during the first week after I bought it from a friend in 2019, when I was still using platform pedals on that bike.
Besides the two or three GCN videos that showed little difference between platform pedals and foot retention, Lachlan Morton finished much, perhaps most, of his alt-Tour de France with platform pedals and sandals or casual shoes, after developing knee pain foot sores during his first few days using clipless. No differences in his average speed, power, etc.
Check some of the news coverage of Lachlan's solo unsupported TdF. The guy is remarkable. He also briefly held the Everesting record last year. He's a member of the EF team, but mostly rides mixed terrain endurance stuff, crazy distances, etc.
Occasionally I'll switch to one of my bikes with platform pedals when I develop knee or hip problems. I can move my feet around freely to suit myself, rather than being locked into one position. Although clipless cleats with float are much better than my old school toe clips and fixed cleats with no float -- in my teens and 20s back in the 1970s, the conventional wisdom for setting up cleats nearly wrecked my knees. I have long, narrow feet with high arches and should have had the shop set the cleats closer to mid-foot. But the conventional wisdom back then was to set the cleats under the ball of the foot. With clipless I can scoot the cleats back a bit, although they still don't quite reach mid-foot. And the float really helps.
The only advantage I've found to foot retention is it enables me to change pedaling styles as I get tired. As I've aged (63 now) my cardio and respiratory have lost some mojo, so I can't spin consistently at 90-100 rpm like I used to. Foot retention definitely helps with spinning at high rpms. But now I prefer a slower cadence, around 75 rpm overall, and on climbs around 60 rpm. So I'm basically mashing. Foot retention has no effect with that pedaling technique.
Still, when my legs tire from mashing up enough climbs, it's nice to be able to gear down and spin for awhile, consciously lifting a bit on the pedals while the quads and calves recover. Early this morning I tackled a 30 mile route that's all rollers, lots of short steep climbs around 10%, hardly any extended flat terrain, and it was nice to be able to switch between mashing at slow rpms and spinning easier gears to keep the overall effort low. This is supposed to be an easy recovery week after three consecutive hard effort weeks -- and I'd done a brisk 6 mile walk in 100F afternoon temps yesterday afternoon, so my legs weren't fresh. But when my legs and engine are fresh, I can't say I really care whether I'm using clipless or platforms because I'm mostly pushing down as hard as I can, not lifting the pedals.
And in casual group rides around the city, I prefer platform pedals because of the frequent stops and slow-downs. Clipless is a PITA when we stop so often. And I've seen several friends fall at stops from not unclipping in time. I can't afford any more falls -- my shoulder was broken and separated in 2018 when I was hit by a car, and exams showed I had early onset osteopenia. Not osteoporosis, yet, but it runs in the family. And the full body imaging showed I had several old healed fractures that I wasn't aware of, especially the ribs. I remember some painful torso injuries but never bothered to go to the ER because there isn't much they can do about cracked ribs. There was no compound fracture, no crackling or risk of perforating my lungs or organs, so I just toughed it out. But I didn't realize I had so many old fractured ribs, vertebrae, etc.
So I prefer no foot retention for city rides. I'm considering switching my favorite old steel road bike from Look Delta pedals to platforms. Turns out one of my favorite running shoes (Atreyu) are great for cycling too -- very grippy on the iSSi Thump pedals on my hybrid, just enough firmness and density in the midsole that I don't feel the pins through the soles.
But I'll keep the carbon fiber road bikes clipless for longer spirited rides. Doesn't do any harm. I'm not faster with clipless but it's handy to be able to switch pedaling techniques between spinning and mashing.