People all have different ideas what makes them comfortable. Some don't like waterproofs as they make you very sweaty - they do.
My commuter had full mudgards - essential. Waterproof panniers - essential.
Light rain, then I'd use overshoes and my 'softshell' had a windproof/waterproof membrane on the front so whold keep me comfortable and not too soaked.
Heavy rain, then I'd use the waterproof overshoes, with waterproof over trousers and a waterproof jacket. Yep, it was hot, but I'd slow down a little. Main issue was to keep my shoes dry. Overshoes alone will let water in from the top - your legs/trousers/tights get wet and it runs down into the overshoe. With waterproof trousers, the rain and sprat runs past the top of the overshoe, keeping the shoe dry inside.
If you regularly get your shoes wet, they start to stink, and you may struggle to get them dried out quickly at work.
I'm not cycle commuting now as I mostly ride MTB, but as soon as it starts getting muddy again, my waterproof winter boots are used. These are fantastic, but expensive. You can't really use overshoes well on a mountain bike as there can be too much 'walking', which wrecks the overshoe.