They're called baffle plates in the S30 microfiche files.

I'm just wondering what benefit they offer on a restomod car with improved calipers and vented discs?

Conventional wisdom says these “help” keep water off the brake surfaces in wet conditions. Also help deflect solid debris that flys around from getting junk stuck in your caliper crevices. Had a honda once that some how ate stones and lodged them in nasty places in the brake parts causing loud disturbing noises and late night phone calls from teen age daughters sure their cars were possessed by demons and demanding I come exorcise them immediately.

Are they “required” no. Do they increase chances of brake failure? Infinitesimally……

First, I want to confess, I removed mine. That said, in the car building process, engineers sit in rooms arguing with accountants about need vs. cost. If it wasn’t needed, it wouldn’t be there.

My thinking, and I'm sure it was what the OE engineers thought, is that if the car was driven in rain or, heaven help us, snow, the shields would do exactly what you two fellows said. But, in a now-fair-weather-only car, I'll leave them off and see how it goes.

Just in case, I did media blast and gave them a nice coating of black POR-15 so they'll be ready-to-go if I ever need them.

The early cars had a scoop built in to the backing plate. but later flattened that out and settled on the ones you have now.

The scoop might have been worse for catching rocks and debris. Trapping it against the disc.