Yeti, no-one is suggesting Sandi plays as a roving forward pocket, it's a matter of degrees and nuance.
In the NBA, the potential of the greatest team of the last 20 years the Golden State Warriors was unlocked when they decided to play without a traditional centre. That meant their already undersized power forward Draymond Green shuffled along to the 5 spot, and had to defend the other team's centres and be the role man on the pick and roll. That is a subtle but important change that allowed them to maximise their historically great shooting at the other positions. That is versatility.
The second best NBA team last season turned their shooting guard (James Harden) into their primary ball hander, and he won the MVP as a point guard They then added the best pure point guard of the last decade (Chris Paul) to the team, meaning the team had ostensibly two point guards. They each had to learn how to play off the ball, and but for injuries might have beaten Golden State. That is versatility.
Even Ben Simmons, who at 6'9 has the build of a power forward and the shooting touch of a house brick was turned into a point guard because he was such a good passer. On the defensive end he defends power forwards, then brings the ball up on offence. That is versatility.
I don't watch a lot of soccer these days, but again, no-one is asking a centre-back to turn into a striker. The versatility comes from wing-back being able to play as a traditional winger, or a striker being able to go wide in a three-man formation, or a central midfielder being able to play a more defensive role in front of the back four if needed. That sort of flexibility allows manager to play different formations.
Not everyone needs to be able to play every position, or even should, but having flexibility in your squad is a great thing to have.
Like Duffield before him, I could see Wilson occasionally being used up the ground a bit more because he's such a good kick (wouldn't you love to see him get on the end of a few handballs and slot one from 55), but at the same time he's such a great kick down back, you'd hate to lose him.
I think Cox will be a better forward than backman, but if A Pearce breaks his leg again I can see him having more value as a backman because we have more cover forward. The question is whether you hurt his development as a forward by also teaching him to play back. Does the experience as a backman help him be a better forward, or deprive him of the opportunity to learn the forward craft? It's not an easy question. Banfield is a good run-with player, but if you only play him in that role do you take away the chance for him to learn how to win the ball. Ideally you should have players who can do both depending on the matchup and the situation of the game.
As for Buddy, the qualifying final we played against Sydney in Sydney was telling. SCOS towelled him up in the 50, so Buddy went onto the wing, and basically won the game for them there because SCOS couldn't keep up with him up the field. That's versatility. If Sydney only played him in the 50 we might have had a chance to win that game.
I think Lyon might have overplayed the versatility line, but I do think you need players who can play a couple of different roles.