Yes, I think it would look too narrow. Also do you have friends that use a walker or a wheelchair? They would not be able to come into your house through that door.

Why don't you just stick with the 12" sidelights and replace the 36x80 builder grade door with a nicer door?

I'd rather have a wider door than wider sidelights.

Get the wider door. People in a wheelchair or walker will thank you, and you will thank yourself when you need to bring in appliances and sofas.

Wheel chairs are made to fit through 32 inch door openings so that shouldn’t be a concern . Anyway you have back door . Do what looks better . I’d rather have trim that matches pretty well then a door that looks off 100% of the time because it’s too narrow . Try to see if Home Depot or another store has a display with the proportions you are considering .

Btw, very few contractors have an eye for design . They are trying to solve a different problem . I would still listen to their advice though .

Yes, 32" is too narrow.