They skipped 30 years because George took a break after ROTJ and here is no way to go back to that period, now.
But they chose to make it a period where several important things happened, rather than progressing the story in a more natural way, so that we could have Empire vs rebels again.
What do you think would’ve been a natural progression of the story?
What I mean is that we saw such a huge jump from RotJ reality to TFA reality with barely any explanation that it doesn’t feel very natural to me. Like I said in a previous post, I believe that the ST is a possible future, but several plot points aren’t developed enough to make me believe that all that happened and everything that has to happen would actually happen.