In answer to the thread title i think the word better suited to semolina is functional, it serves a purpose like Nick says a s a binder mainly as its make up is mostly carbs which carp cant do anything with, as for the Nutrabaits Addits they were more additives rather than making a bait a HNV based bait, i used to know what all 3 were, i think taste was MSG but i have forgotten the other 2.
I think the fact there are a lot of very good products available now and the way modern day anglers use there (glugs, coating boiles etc..) i think it would be very difficult for carp at first glance to tell whether something is good for them or not as you could make a poor quality boilie initially seem like a likely food source, and fish dont have hands so the only way is to try one and find out, if you eat something that is like digesting a stone your porbably not going to go back for more.
A thing that does intrest me is do we cause sensory overload and what the effects of that are to the fish by having most of our baits pepped up