I've never seen the point or felt the need to use clipless pedals. I don't wear Lycra or padded cycling shorts either. My approach is just to go for a ride when I feel like it or it is the quickest most convenient way of travelling a few miles. I'm not interested in maximising either speed or power output. Clipless may well have marginal benefits for racing or keeping your feet in place if riding a fixed gear at high cadences, but for normal utility or recreational cycling I regard them as pure window dressing.
In fact, in one respect they are worse than flat pedals, because they are footwear-restrictive they remove the spontaneous aspect that can be positive about cycling. If you have flats, you can casually hop on and go somewhere without any pre-planning, because you can ride with whatever footwear you already have on. The way I look at it, the less faff and ritual that going for a ride involves, the more often you are likely to actually choose to cycle.
Essentially I would say cyclists fall broadly into two camps. There are those who take it all really seriously, with power meters and ride data and training plans and nutrition. Most of this camp will favour clipless.
Then you've got the casual flat pedal camp who just don't care about things like speed and power, but enjoy cycling in a more spontaneous and less scientific manner.