It's not so much about being harder as about making progression meaningful. It's no longer a matter of generator - macerator - bunch of solars - massfab - game over. There are many paths through the tech tree, multiplied by the cross-mod compatibilities of GT. Most of the shortcuts of IC and workarounds through other mods have been cut or patched. Advancing through the tech levels needs time, work, planning, and genuine research because the possibilities are so vast (unless you're satisfied with just copying someone else's setup). But building every new machine, getting a new ore, metal, alloy, or solution is so much more rewarding.