It's kind of important when Buch is proven on the first line and he pushes everyone down on the chart.
I'm not convinced Buch is getting moved. The aforementioned depth is one reason. The chemistry of the 1st line, and it being probably the only returning line from this season.
Trading him for a defenseman most likely means 4 D protected in expansion, not insurmountable but another can of worms. It means that adding a #2 center on anything more than 2 years exposes Chytil, Lemieux, Howden, and Fast (if re-signed which I assume with Buch out). Protected 8 skaters: Panarin, Zibanejad, Kreider, Trouba, ADA, Lindgren, #2 center, added LD.
In other words, moving Buch for a LD means we move the deck chairs around and expose a hole on the right, and you can't add a long term solution at center. I'm comfortable with Strome on the short term but that doesn't seem to be a popular take. Or you have to move ADA which is even less popular.