Exactly.
It's nice enough that they got enough development out of Etem to call him a fringe/bottom-tier NHLer - but unless they develop beyond that journeyman/fringe tier of quality...once these types are out of their ELC and/or exposed to waivers, they tend to start floating around the league and it's really not a big deal.
It's too bad Etem didn't reignite the type of potential he was drafted on as an actual goal-scorer of some magnitude, but he didn't...and now he'll float around the league for a bit.
And right now, Skille is the better player. He was the better player for the role last year. And it's highly likely he'll be the better player later in this season as well. He's got years of experience floating around like that learning what it takes to stay on a roster and honing his game in that role as an NHL journeyman. Etem is just starting that journey.
The only reason a loss of Etem matters a lick, is if you really think there's still more "upside" to give there. If you think he can still mold himself into a quality Top-9 Winger. Personally, i'm ready to pretty much close the book on the possibility of that. So who cares? We swapped a fringe "asset" for a slightly better fringe "asset". that's a + value, however negligible. It doesn't matter that Skille is older, as neither he...nor a 13th Forward calibre Etem were going to be around for much longer than a year or two anyway.