I think you might be underestimating how good Ehlers is at passing and opening up space. He actually has better vision than Wheeler and is excellent at gaining the zone on the right side and then opening up to pass to his left wing. I think that with either Ehlers or Wheeler on RW with Laine, it's "pick your poison".
No, I'm not underestimating Ehlers at all. He just is a left-handed shot and that is all.
For a line like this, everything feeds to the shooter. You want Laine to always be able to one-time off a pass. Passing to the left is by far the most comfortable for right-handed shots. You want the center, the right winger, and the right defenseman to all be right-handed so that they all can comfortably give a quality pass to Laine for a green shot one-timer high quality chance that crosses the middle of the ice(Those have like a 30% chance to score(straight in or off a rebound) on average and that is going to be much, much higher for a shooter like Laine). When you have an asset like this and the chance to maximize its impact, you in my opinion should do so.
A player like Ehlers would of course be -possible- if there is no alternative, but when someone like Wheeler exists and gives you a perfect "everyone-feed-the-shooter"-setup, there is no reason at all to go out of your way to stick Ehlers in there. Especially as I just consider Wheeler straight up better and he'll be useful in a leadership role for the young Laine.
Now, saying Ehlers is a better passed than Wheeler is debatable at best. Nevertheless, even if that was true, the handedness would certainly tip it in Wheeler's favor. He just had over 50 assists. I doubt he's all that bad at passing.
Also, Wheeler is much better as a net front presence and just being big and strong, gain space and tap in rebounds. Someone needs to fight along the boards, do hard work and actually gain the puck and Wheelers is one of the best players at doing things like these in the entire world. Ehlers really doesn't fit, I'm not sure why so many are pushing it. Even if it was only about passing it'd still be Wheeler, but when you add everything else this is obvious.