The "controversy" stems from the comic/sci-fi/anime nerd concerns about "purity" or whatever--that Macek essentially bastardized a bunch of original Japanese shows to recreate his American phenomenon. Often, the "defense" of Macek's pillaging simply repeats Harmony Gold's explanation that they needed a show that could run every day--like Transformers did--and any of the three series that eventually made Robotech didn't have enough episodes and so, they had to be combined. This may have been the "business" decision behind the idea, but whether it was there from the start or a really awesome byproduct of a business decision, what Macek did to create Robotech was much more than a pragmatic television scheduling decision, Like so much popular art, there's a mix of art and commerce and a little bit of "smuggling" involved.
Macek grabbed from these shows, and then, tweaked the plots and characters however he saw fit and made something that was, yes, better than its parts. If you're aware of the weird, twisty-turny construction of Sir Thomas Malory's Le Morte d'Arthur, what Macek did is similar: He retro-fitted a bunch of stuff to fit his own interests, obsessions, and dramatic expectations. I'm sure I'm not saying anything mind-blowing here, but because literary critics are smarter than comics critics, they find what Malory did really exciting and interesting and not offensive or just plain wrong or whatever. For chrissakes, Malory raped a nun and his reputation in his respected field gets discussed with fewer caveats than Macek's.
Perhaps, I've just got the tragic death of Gang Starr's Guru on my mind (take four minutes to listen to this please) but the weird view of Macek's legacy--he's at best responsible for opening the doors for anime but not really respected for Robotech, he's at worst a hack and an opportunist--and the objection to Macek's artistic compiling seems rooted in the out-dated anger with musical "sampling".
Issues with "sampling" shoot from plenty of different angles, but they all funnel into I think, a fear of something, anything, everything, being unstable. From that Led Zeppelin song you love to all your precious fucking Japanese cartoons. Comics fans--like rock fans, the main opponents of sampling--are deeply traditionalist and so, there's a concern with origins and propriety. How does Macek's reconfiguration of these other series negatively affect the original series? This is made even more complicated when you realize Macek took the time to reissue, remaster, and translate all the series' he "stole" from.
I prefer to think of Macek as a master sampler and mash-up artist. That because he was this producer guy, he had access to the materials that now, twenty-five years later, every tween or grumbly old bored retired weirdo can also access. In short, he created a lasting, meaningful, "mash-up" called Robotech and it was this insane, generations-spanning, deeply-moving space opera, not say, some DragonballZ clips edited to Linkin Park--which you know, has a purpose too.