Suspension does add comfort and is important in maintaining traction and control over rough surfaces. Good frames are designed with vertical compliance built in. Tires, wheels, saddles, stems, handlebars, your knees and seat posts can add more vertical compliance. Passive suspension is more than enough for most road riding without adding the weight, complexity and maintenance of mechanical add-ons.
Comfort and handling can be improved by adding a good quality suspension seat post and stem, (I have a Cane Creek eeSilk post and stem). I also use supple tires at 40 psi.
Unfortunately, most ebike suspension lacks rebound damping and is not very tunable, (basically having a double barrel pogo stick). They will still soak up the bumps, but steering precision and control suffer.
I have nothing against good suspension, but if the bike is designed well and only ridden on smooth to moderately rough surfaces, it’s already there.