Yes, Greg added code (which is now gone, last time I checked) that checked if his configs were forcibly changed by another mod to cause a crash. Yes, that's not a nice thing to do. However, Greg gave everyone a choice whether they wanted the wood nerf/balance (Yes, balance. There's a reason for it and it's not just to make the game harder.) by adding a very visible config file that they were free to edit and takes at the most, 1 minute to change.
Tinker's Construct added code that detected GregTech's nerf/balance config for wood>planks and overwrites it to force it to the default version. Thus, Removing that choice for everyone. Whether they like it or not.
In this case (A short case. Lasting around a day and has already been fixed on both sides), Greg was a bad boy. But it IS his mod and he can do what he likes with it. The end user has no say in whether he should or shouldn't do it. The only thing right now, that the FTB community has a say in, is whether or not it stays in the FTB pack. The FTB developers don't edit GregTech, they don't make it or update it. So complaining here means nothing to Greg. If you have a problem with it, tell it to him on the IC2 forums. Just remember, that the same thing has been posted there enough times to be read and adding a copy of the post in his thread won't stop him from doing it next time another modder forcibly removes his config options. Also, spamming his PM box on the IC2 forums with how much you disapprove of his mod/methods is probably a bad idea, as that means he'll just empty his full inbox without reading anything and probably delete some important message from mDiyo or some other modder asking for some changes in regards to their mod. Which will make it the fault of the end user if their favourite mod stays/gets nerfed (has already happened once today).
The mods Greg alters are also free to add or change their recipes, or more preferably contact Greg about a compromise on his nerfs (Which he will most likely do if contacted). Btw, stop blaming Greg for the recipes of Advanced Solar Panels. Those were done entirely by the mod author, independent of GregTech.
As for the people raging against why people even use GregTech: It's because they want to. Because they feel the nerfs done to vanilla and other mods bring balance in the progression of each tech tree between all the disconnected mods and prolong the gaming experience. Dismissing other's positive opinions regarding GregTech simply because you don't like GT is utterly childish. More so for an extremely vocal member on these forums who seems to think himself qualified to proclaim GregTech as total trash and anyone who likes it to be either mentally handicapped or suffering from Stockholm Syndrome (which imho, should warrant an immediate ban for the countless times he's said it to various members. Not to me, mind you. I stay out of these things normally. It's no different from a religious debate since it deals with people personal feelings and nothing else.)