Given that a front mech and inner chainring add up to about 200g in weight, and the road racers love of close ratios, it’s easy to see why they don’t bother.
Makes far more sense to us MTBers coming over to road riding though, without the requirement for single tooth gaps almost all the way up the cassette, it does make for slightly less maintenance, and less chance of dropping the chain on the front due to a missed shift. Of course these things are far more important offroad though, on an MTB or CX bike.
A word about ratios though… If your regular rides mean you spin out even a 50/12 ratio, you’re either need to learn to spin, or to tuck into an aero position. I can spin a 50/12 up to around 45mph, but by that time I’m better off getting into an aero tuck as far as speed goes! I thought I’d miss the 11T cog when I went from 11-28 to 12-30, but not at all… It just prompted me to get into a tuck earlier, and subsequently I’ve gone faster down a number of big hills locally since making the change, presumably as I stopped pedalling fruitlessly earlier on!
Also, the racer’s favourite setup of a 12-25 with 39/53 chainrings gives a 283% range, whereas an 11-32 cassette on its own gives a 291% range. An 11-32 cassette with a single 42T chainring gives a top gear equivalent to 50/13 and a bottom gear equivalent to 34/26. Certainly makes sense on a commuter bike to my mind, or even half decent paced club runs. Anything short of Crit racing or massively hilly Sportives or the like I’d say… In fact, I’m keen to give it a go… SRAM Force CX1 here we come! :-p