I noticed that Gregtech was shortly supporting higher verision of minecraft like 1.10.2.Why did the team stop to develop on the higher version of minecraft and stop in 1.7.10?

I never actually started developing for 1.10.2 so I have no idea what you are talking about? Maybe you are referring to some of the other GregTech Ports which do exist for that Version? Edit: also developing mods for those newer versions became hell thanks to mojang and forge