Bait in, time to set the hook
You are missing 1 huge aspect of the mag and AGD. The valve is part of the gun, it is almost unibody like a car; in that the valve is part of the structure of the gun. With that it is incredibly hard to stop what you are doing to change in midstream to go an entirely new direction. Looking at those guns of that era, Bob Long kept refining the stacked tube design that he learned off ICD. Dye bought up matrix and everything Gen-E and War Machine(?) had done before, again refining the design. The same with WDP, even though they kept trying different sensors to detect paintballs that either a reflective or breakbeam eyes. SP was the only ones that did change the entire gun, but as far as i know, the development of the SFT could have been years in the making. Whether SP saw that the development path of the old shoebox was basically nil, or they could not compete with the RoF wars with that closed bolt design.
But because you said development, this also goes into the C&D that SP started. Though slow to pick up ground as people didn't or wouldn't believe it, the ominous spectre of that did kill AKA's Viking and Excaliber, force ICD to sell out to Empire then fold paintball activities by 2006, and a few others i can't remember. That more than anything potentially stopped AGD from doing any development to refine or even go a different, possibly a true blow forward electro.
The freestyle was an elegant design but it was as temperamental as an F1 car. The first models had horrendous efficiency but each generation did refine the gun (though the FSP was the basturd step-child that well was a basturd in design and implementation), to the point that if development was not stopped and ICD did get some decent HPRs that could keep up with the gun's potential. (Pssst, there were rumors of Empire planning to use the Freestyle FS8 bolt in the Vanquish, but they chose to go with the more recently acquired SP shocker properties)
So again, like an arch, you just can't focus on the keystone but all of the factors to the one thing. Everyone here in this thread is absolutely correct because most of these people had lived through that era. This is an opinion question, not something you can do a quick "sound byte" for an answer because there are and were so many factors that played major and minor parts. I knew you woikd give your quick, "cut bait & start over" answer because that is who you are. Even that isn't wrong except when considering all the factors in that time.