Well, when you've been impaled by something, you don't cauterize around it and call it a day. Your splinter is half the size of the planet, that's like having a 1m-splinter embedded in your stomach, not very convenient. Additionally, correct me if I'm wrong here as I didn't follow in details that story, we have no way to be sure this sword isn't cutting through an important "system" or even the Titan's body itself, right ?
Anyway, yes, it's just another scar in Azeroth. But unlike other scars, it was completely forgotten and never mentioned anymore. The Maelstrom or Hyjal had recurrent follow-ups throughout the extension with some quests asking us to visit the place for whatever reasons, so at least you know it's monitored somehow and still exists.
(talking about that, we'll see if Teldrassil is mentioned at one point in Dragonflight or not

)
The sword was a less-than-one-expansion problem, despite it should have been way more than that.