If you learnt to skid with clips/straps it's possible that you may have picked up the habit of rotating your foot a bit when you skid. Obviously if you twist your foot too much with clipless you will unclip and could wind up in a spot of bother.

The only time I've ever had probs with unintentional unclipping on Time Atacs has been when my cleats were worn out, and it's easy enough to make sure they're replaced when needed.

Also, I never have any issues with walking comfort or lose any sleep over looking like a bike dork wearing carbon sole MTB shoes whenever I'm riding -- or even out at the pub or wherever. I'd even go so far as to say that I think it's a kinda cool look, though I may be somewhat delusional on this point, and certain clipless shoes definitely do not look cool.