One unexpected advantage of composite/ resin pedals is that in a crowded bike space such as mine they are less likely to gouge the paint on your other bikes.
As to flipping over toe straps , I think it's just a knack. Some pedals are better than others. I had a pair of platform pedals on my old Claud Butler which had done good service on previous bikes but for some reason gave me knee pain after longer rides on this bike. I bought a pair of cheap resin pedals which could accept clips and straps and the knee pain went away! Possibly they allowed my feet to move outwards slightly and it was enough to take whatever pressure was on my knees away. I think that they were Wellgo.
When I bought my used Revolution tourer I was ready to do the same thing but it came with double sided pedals, suitable for clips and straps on one side, and clipless on the other. Although they were in good condition, I couldn't make out any maker's name. (Edit -they are Shimano. No idea which model). The toeclips make them hang upside down but somehow when moving off my toe makes contact with it quite naturally, and it flips over and accepts my foot without effort, even if I haven't ridden it for some time. There must be an element of muscle memory and "what you're used to" but this is definitely one of the ones that is better than others, for me.
I have had the odd creaking or clicking pedal over the years but never had one fail on me. They have either got horribly scruffy or rusty with use and been replaced or been sold with it when I sold a bike.
As for the original topic, for a bike that is used round town where there are many junctions or on surfaces where you might need to get a foot down in a hurry, flat pedals have a practical purpose. Perhaps not completely in tune with a sporty image, but they work.