Unsolicited advice incoming!
How old are the children?
Personally (and this is coming from someone who used to be a dreadfully fussy eater), I would just cook one "family dining" style meal an evening. Put all the components separately on the table for people to help themselves (so veg doesn't have to touch anyone's plate 
).
Don't stress over what people will like or what they won't eat.
You just focus on doing your job - to provide a nutritious dinner - and they can worry about how much of it they're willing to eat.
Anything they want in addition to this meal can be paid for, shopped for and prepared by them.
DSS doesn't sound like he's getting any real nutrition at all, and this needs addressing pronto. My parents made no attempts to address my fussy eating, and my adult life has been plagued with a plethora of health conditions that have been caused by childhood malnutrition and eating a diet very similar to your DSS. I would barely eat anything, only dry food: chips, toast, maybe cheese on toast on a good day. When I went to boarding school at 16 and was made to eat dinner round a table in the way I've described, my eating problems vanished in a term. I still won't eat some things, but no longer do I get cooked different or special meals.
Your DH is not setting a good example at all. The issue isn't that he made your DSS the family pizza (although he was BU to do so), the issue is the fact your DSS wouldn't eat anything else and that your DH was more than happy to indulge this.
I'd be less concerned that cooking all these different meals is stressful and time consuming, and more concerned that members of my household we're lacking nutrients. The problems from a poor diet don't show up right away, so my whole childhood my parents just shrugged it off and assumed I'd be fine. It's terribly frustrating to eat incredibly well as an adult, knowing that however much I try, I can't reverse all the damage done in those formative years. Think stunted growth, brittle bones, terrible joints. Pain every day.
Your husband, quite frankly, needs to get his shit together.
Now I might be reaching here, but it seems his influence is causing problems. It seems your oldest DD has no issues - did she learn to eat well before he came into the picture? Your SS seems to be the worst eater, with middle DD picking up on his habits.
I absolutely cannot fathom an adult that won't eat vegetables. I hate the things, can't abide them at all, taste horrible to me. But I still shovel them down, because they contain stuff that my body needs and my DD needs to see adults eating like normal people.
I just can't picture it, I've known many a fussy child, but an adult? Where do you go out for a nice romantic meal? Pizza Hut? McDonalds?
Sorry if I seem like I'm jumping down your throat, I don't mean to be goady, I really don't. I just wish an effort had been made with me before long term consequences had been secured. Make sure your children's nutritional needs - macro and micro - are met. Please. It's neglectful.
& cooking only one meal will only save you time, it's a win/win.
TL;DR - yes, your DH was BU for cooking the pizza. YABVVU (assuming these aren't all adult children) for not feeding your children properly. Super noodles aren't a meal.