Time Travel stories are fine to me in the "if it has already happened, it will always happen" sense, but I've always found time travel as a way of undo-ing past events is the ultimate cop-out from a story telling perspective and removes the dramatic impact of anything that happened before time travel was used to "fix" everything.
For example, the episode before last was awesome and had a ton of awesome stuff happen (Cisco's death, the chief getting injured, Barry's step dad captured, the painfully awkward Barry/Iris relationship stuff finally resolved, and the entire city at risk by a massive tidal wave), but because of time travel, none of that mattered in the overall story. That awesome episode might as well not exist anymore except in Barry's head.
It's an interesting concept from a sci-fi perspective, but from a storytelling perspective it always ends up as a super lame deus ex machina or reset switch. I'm sure they'll pull a Back to the Future 2/Flashpoint later on when Barry tries to save his mom, but for the moment all they did was undo all of what made that episode great.