Riot, can you explain what 'remakes' are and why they happen?

Some of you may remember the issue of Sejuani dashing over a wall and ending up back at her original location at MSI. It was very similar to this

https://www.youtube.com/watch?v=bqtDNH9kRYM

I guess these are called 'remakes' and they happen when a champion attempts to dash over a wall to a location that is still part of the wall. I was under the impression that when you did that your champion just smashes their face into the wall like a dumbass when that happens. You know, like those fail flashes that make you feel like a complete idiot. How come in these instances your champion clearly makes it over the wall and is the forced back to their original location instead of just colliding with the wall? I would rather feel like and idiot than feel cheated...