Ironically, Alpha Strike plays more like book battles than the standard game does.
And suddenly nothing could be further from the truth!
Most of Stackpole's battles were directly tabletopped out, it's true. The small-scale battles in Grave Covenant, for example (one of them even appears in The Dragon Roars book), or the Awesome vs. Victor shootout and Yorinaga Kurita vs. Morgan Kell during the Warrior Trilogy.
However your assumption here is gravely in error, because the books were carefully considered on this point. As an exercise the DSC forums went through the entirety of the Twilight of the Clans series once and did the Mathhammer to determine how accurate to the tabletop all the battles were. Only one didn't pass, in Exodus Road. That was the reason I actually learned the AeroTech 2 rules, so I could evaluate the WarShip combats attending Operation Serpent since the only other person who knew them outright wasn't interested in the project. (They pass with flying colors.) As a personal thing I applied similar logic to Operation Audacity once, because something struck me as wrong; it passed when I broke out the rulebooks to check.
Alpha Strike, by way of contrast, really doesn't work for some of the longer campaigns in the books precisely because of the mechanics regarding the interaction of large and small 'Mechs you've described. The "weight decay" you see in large-scale battles or long campaigns where the small get knocked out first just doesn't play out in Alpha Strike as people combine fire to knock out the large 'Mechs first in ways that are not feasible in the original rules.
Someone checked to make sure the armor values and weapon damages all added up at the end of the day, at least in the old novels. The stuff since Dark Age hasn't been as rigorous.