Good rant. Stuff should not fall off. Big culprits:

Those taillights (PB and PDW) that clip to the little loop on the seat pack: you have to zapstrap the end of the clip so the light doesn't fall off. Yeah, I've had the cheap, free blinkies that clip on fall off. It's more a safety issue because now you don't have a blinking tail light, but you don't know it.

Light & Motion makes the worst handlebar mounts. I had a previous model that was actually intended to break off in a crash. The problem was that a hard bump would also dislodge it. Their current rubber mount for the Urban 500/300/180 is OK, except that it looks very vulnerable to breakage. You can order a spare for $10, but shipping is $15 (or $75 to Canada!). A spare should come with the unit.

Sigma computers are very reliable in the rain, but they changed their mount to a twist-on (from a slide-in) in 2003, and the computer is prone to untwisting itself, as it doesn't really lock securely. Even pushing one of the buttons the wrong way, or wiping rain off the face in the wrong direction will untwist the computer enough that it comes off; I've had it happen a couple of times. i do not like losing a bike computer, as I record daily and total annual distances off it. I would expect more from German engineers.

Luis