I spent 25 years off road with toe clips or SPD’s and only gave flats a try at the beginning of the winter on my rigid bike. I’m wishing I’d done it years ago and I’ll be buying some for my hardtail soon as well.
For me I just feel more comfortable knowing I can get a foot down more easily and without giving it conscious thought. I thought I would end up putting a foot down more often although in reality it’s the opposite. I also thought I’d be constantly worrying about my feet slipping off the pedals but so far using some very ordinary shoes and only the very cheapest pedals with only small “moulded” pins this hasn’t been a problem. And that’s riding off road every day to work and back through the whole winter.I also find moving my weight around and controlling the bike in that way easier.
If I were a more skilled or confident rider then the advantages of SPD’s might make me stick with them, but the simple fact is that I’m not and I’m enjoying riding more and that in the end is the only criteria that counts for me.