Not everybody wants to spend time learning all about the intricatcies of Nutrients. They want something off-the-shelf that they can throw in and "ferget about it" Some aren't necessarily lazy, or brain dead, but practical. If I had a 99 plant crop I wouldn't want to stress over nutes and PH. I would have much more pressing things to tend to. Considering an OZ brings in $300 on the average, who would give a rats ass if these nutes were twice that of others, as long as they have the rep of returning bumper crops. So as a level headed businessman, one shouldn't fret over expenditures that are maybe 2 or 3% of revenues. I would be more concerned with electricity, security, water purification and CO2.
AN and all the sups are for the big boys, not practical for micro grows. However, by them combining the Aminos, f2,h1 and wet betty in the 2 and 3 part bases, they are appealing to the small guy who didn't want to buy the discrete sups. Good marketing.