Off-road and race vehicles also tend to get new sets of pads and rotors after each race- does your rig?
They don't run them to ease maintenance, and to reduce unsprung weight. Unless you plan on servicing your brakes regularly (think weekly), or live in an area with no rain, snow, ice, dirt, etc. (A.K.A. NOT CO
), they're worth it.
The purpose of dust shields is to keep crap (debris, water, mud, sticks, etc.) out of your rotors and calipers. If you're off-roading, they are absolutely worth it. After a big wheeling trip, it's not awful to pull the rotors and calipers off (not disconnected, but removed from the hub) to get all of the crap out of there.
As a former race mechanic (more on the driving side, but I often had to perform my own services when I was racing on my own), I can tell you- when minutes count, yes, it's fine to live without dust shields and other non-essentials. For my daily driver, I wouldn't dream of living without them, especially on something I wheel- Mark W.