My rain jacket has a hood and is adjustable so that it will fit over a helmet or fit fine without a helmet. I can't recall a significant reduction in peripheral vision, at least nothing like when wearing goggles (which I need for cold and blowing snow). I currently do very little riding in traffic so most of my attention is focused on the MUP or on my rutted, icy residential streets.

I got the rain jacket when I lived in an area where it rains a great deal more than it does here. It was common for it to rain, sometimes very hard, with the temperature in the mid 30's F. Times like that keeping cold rain from running down the back of your neck (not to mention off the rest of you) is well worth having a hood. Also, the jacket has draw strings to keep it from blowing off. If it did not, I wouldn't bother with a hooded jacket.

My rain jacket is also lightweight and compactilble and sits in a frame bag with rain pants ready for duty.

I got this jacket after years of unhappiness with cheap rain suits that invariably tore and were in other ways inadequate, like with hoods that blew off.

So I'm with the OP in that a rain jacket without a hood seems odd.

I wonder if anyone makes a quality rain jacket with a zip away hood.