I do get your frustration. Whenever an episode is over and I don’t feel like the “main” plotline has been advanced I can feel a little let down. But drawing on the experience of watching Lost (which is probably instructive, given the pedigree of Eddie and Adam), when I look back at those episodes, I often find that there is more there than I originally thought. I am not suggesting that there is NO “filler” along the way. They can’t tell their story too quickly or they will run out of plot by the time the first season is done. But I do think some of the seemingly lesser plot lines advance the themes of the show as a whole.
I also think it is too early to tell which characters will end up being important to the overall story. They spent a lot of time at the beginning with a couple of main plots — Henry and Emma, Snow and Charming, EQ and Rumplestiltskin. And I think they do that to draw people in and get them invested in the show. But in telling a complex story, you can have a lot of side plots and peripheral characters that enrich the overarching plot. I don’t think we will know until next season, or the next (knock wood) or the next, whether Hansel and Gretel were anything more than a creepy new telling of the Hansel and Gretel story, or whether Nova will end up influencing major events, or whether Malificent is a major player or just a washed up unicorn lover.