alt Hacker NewsI remember Greg was actually a pretty controversial modder back in the 1.5 - 1.7 days. Many people did NOT care for the Factorio-like direction he took IC2 in (before Factorio was a thing! Apparently they cited IC2 as an inspiration), and at least once I think he accidentally inflicted that gameplay on modpacks which didn't expect it, removing metal block recipes as I recall. But it's very cool that his mod should get such a legacy.
He was just ahead of its time in terms of grind and realism. I remember one of the first times gregtech was introduced to the mainstream was with the Mindcrack FTB modpack, most people hated it because they were used to being able to unlock ore doubling (with the ic2 macerator) within the first 20 minutes of a new world. He increased the difficulty by making the recipe need diamond cutting heads instead of a ton of iron. As you said he did this by modifying another mod's recipe (in this example ic2) which was frowned upon at the time.
In a sense, he created expert mode modpacks before they were a thing, where it is common and expected to modify recipes from multiple mods to make a more interconnected recipe chain.