I think some people or missing a crucial human factor when complaining about people complaining about GregTech changes. We humans are competitive, and like to at least compare what we are able to accomplish against what other people are able to accomplish. What that means with respect to configuring GregTech, and modding in general, is that we can't just all quietly go and configure our SSP worlds to just how we prefer and never speak of it to anyone. We want some consensus on a configuration so we can meaningfully talk to each other about our accomplishments. For example saying "I just set up a quarry in my mining age" implies a whole different amount of effort if I am playing wgt or ngt. If we throw up our hands and say "Everyone go configure however you like and make sure not even the NSA finds out what config you are using" then we will not be able to talk to each other about our accomplishments meaningfully.
The above does not even touch on SMP servers. On a server, you will need a consensus on what the configs will be, as everyone will need to use them. This cannot come about without people discussing what they like and dislike about the mods, and the config options. So I cannot agree with people who say "If you don't like the configs as shipped, shut up and change them yourself". I can go along with requests that criticism be more constructive, and people who have nothing more to say than "GregTech bad! Boo Hiss" shut up and let more reasoned discussion happen.
Now there is also a reason that GregTech gets a lot more heat about changes than most other mods. Say for example I am interested in setting up Forestry farms and bee breeding, with a little BC automation, and using MFR to set up an automated cow farm with just enough IC2 to power MFR and provide a diamond drill. Now it wouldn't matter to me if Thaumcraft, TiC, or most other mods are installed or not. But Gregtech (except on the "super easy" settings) being installed will impact on what I would need to do to implement the above. So on choosing a server to play on, I would not care much if these other mods were installed or not, I could easily ignore them. However I would care if GregTech is installed, as it goes beyond simply integrating with other mods and actually modifies them to suit the GregTech vision. That is why you have so many people commenting on the Gregtech impact, as opposed to example Forestry changes.
In short, can we promote reasoned discussion on GregTech options (no GregTech is an option), and avoid hating on GregTech or hating on questioning GregTech "as shipped"? Oh wait, this is the internet. Still one can always hope.