perhaps the people that don't have problems with spd style pedals don't ride as much as i do, but then again i'm a courier. so let's see...

i've ripped the cleat out of the bottom of a shoe.
i've delaminated two pairs of shoes- a pair of northwaves adn some times.
i've worn out a pair of crank bros cleats in about 3 months.
any sort of manoeuver you want to perform that involves moving your bike/rear wheel laterally, ie, skip stopping or nose wheelie pivots come with the risk of accidental clip outs.
also, yah, if your cleats get too worn you get pop outs during skids, or if you're pulling up hard with your rear foot.

spd's are great for speed, climbing and spinning. straps and cages are better for tricks, wearing comfy shoes and having a wider platform (depending on shoe and pedal)

try 'em both out with your riding style and use what works best for you.