With this trick, you can effectively counter heavy frontline-based compositions in the early rounds such as Clash, Trundle, and Vanguard. Taking the longer route mentioned above will make your frontline harder to reach and will output a significant amount of damage. However, this trick seems to only work with Urgot when this unit usually stays in the third row and requires the protection of Yuumi. While other units with large attack ranges tend to stay in the back row and do not need this ability.
Of course, despite being a useful trick, it still stems from a game flaw, and Riot Games needs to address it as soon as possible. It is highly likely that in the upcoming 12.1 patch, Riot will revert Yuumi to functioning normally and no longer create an 'invisible wall' as before.