Then never play Gregtech... because there's not all that much you can do with it that can't be done with another mod better. Whether that's more challenging, faster, easier on system resources, or whatever you want to name. He didn't have any particularly innovative content before I stuck him and all his mods in perpetuity on my permanent blacklist, he apparently did some stuff with the things in the place since then, but knowing greg? It's just "HEY! IT'S LIKE THIS STUFF YOU HEARD OF BEFORE. Only... GREGIFIED!"
A) Not just slightly. BigReactors output in kiloRF right? A Tokamak fusion reactor outputs in the millions.
B) I can find a use for the total output of a BigReactors reactor pretty easily. MFR Lasers for one. I can't recall... do ExU Ender Quarries speed up when fed more power? Even if not, the major use in Reika's mods is a simpler method of transferring his shaft power. With cross-dimensional transfer it allows you to save the render lag and such from the fusion reactor, and then power your disparate Rotarycraft machines anywhere. Note that the conversion from shaft power to RF means some of Reika's machines use RIDICULOUS amounts of RF to operate at reasonable speeds. Also most of them can be pushed to obscene speeds if you need them to (which can be required for certain playstyles)
The other thing is that many of these megareactors can be community projects for a community power channel. I certainly intend my reactors to do this for my server