Warning: I said filler episodes ruin shows, then one changed my mind
I used to skip anything labeled filler. Straight up. A friend in Boise kept telling me I was missing stuff and I just laughed at him. Then I hit a wall with a long running show and had nothing else queued up, so I let one of those episodes play instead of jumping ahead. It was a quiet one, no big fight, just the crew hanging out and one character finally talking about why they never go home. Halfway through I realized I cared more about that than the arc I was rushing toward. The whole reason it landed is that the main story never had time to slow down and show me that side of them. Now I look at filler differently, like it is where the characters get to breathe. Anyone got a filler arc that actually won them over, or am I the odd one here?
Filler is underrated, plain and simple. The Star Trek TNG episode "The Inner Light" gets called filler sometimes and it is one of the best hours of TV ever made. No phaser fights, no big bad, just Picard living a whole other life in 45 minutes. That episode does more for his character than half the action ones.