I think the crux of the problem (or at least, one of the cruxes) is that people play the game differently. Everybody has their own ideas of fun, or what makes a good game. Some like to shoot for the "God of all the universes" as fast as they can, while others play the humble caveman, slowly making his way towards industry. And that's fine, Minecraft is more of a platform than a game. The ultimate sandbox, where almost everybody have their favourite ways to play, and mods to further diversify it.
Thing is, modders also have their favourite ways to play, and they like to make their mods accordingly. Greg's idea of fun seems to share many elements with mine and many others' (great big machines, search for rare materials, end game content), but parts of his preferred play style also clash with the opinion of many others (hard to acquire basic materials, limited access to powerful technology including that added by other mods), which makes his mod a sort of double-edged sword (I'm sure there is a better anecdote, but English is not my main language and it's late in the evening here. Sword will do for now).
What's the "right" way to play Minecraft? Simply put: Start the game, do whatever you want from there. Whether you like being overpowered or prefer a drawn-out challenge where every machine is a milestone, you can find mods to suit your needs. Or, heck, make them.
Greg did. Many of us loved parts of it. Greg probably loves all of it. That's his opinion. And his mod, so he's free to do with it as he pleases. If you want the stuff he has to offer, you have to take the whole package or use an older version. The choice is yours, and for some, the choice is tough. And the frustration of that toughness is what makes us angry. We want the good parts - whichever parts that is - but not the bad ones. However, it's all or nothing. Tricky question, but that's the question Greg asks.
If you want half-and-half, Greg is sadly not the one to provide it. And we shouldn't be angry because of that.
