I don't think anyone is arguing he'd make us better on the pitch.
You are completely ignoring why he was banished to the under 23's. Just so you understand:
1. He took fat burners without the club's consent. You don't need to be a genius to realise you are taking a massive risk doing this
Did you miss the bit where the case had been thrown out because it wasn't on the list of banned substances at the time?
2. He missed a pivotal part of last season because HE choose to take fat burners without the club's consent. Hurting himself but more importantly the club's chances of winning a trophy AND getting CL qualification
Not only this but he missed the Euros in his home country - for what turned out to be a none-crime
3. In the 1st week of pre-season, he infringed club disciplinary measures on numerous occasions
And he apolgised for it, to put it into perspective Firmino was charged with drink driving, he endangering his life and the lives of innocent people, but has still received unquestionable support from Klopp. My point is that Sakho's crime did not deserve the punishment of being frozen out for months - if you look at Chelsea and at how Conte handled Costa's outburst; it was the perfect blue print as to what should have been done with Sakho; take him out of the team for a few weeks and then get him back in the fold.
Klopp's point was made "don't fuck about", but he cut the nose off to spite the face, we needed Sakho when we played Klavan, we needed him when we played Lucas out of position - Klopp should have saw this - especially as he didn't buy an upgrade during the January transfer window - It was poor management of resources and has cost us a title challenge.
4. He refused to go out on loan at the advice of the club
Fighting for your place is now a negative? Especially when he's the best defender at the club bar Matip (who's in his first season and plays on the right hand side of the defense and is a perfect partner for Sakho)
5. Via social media he started moaning about his exclusion and the manager. 24 Hours before an important league game.
That's because he thought the club was lying about his availability saying he wasn't fit when he was.
It was after this multitude of discretions that he buckled down for a few months with the under-23s. The horse had bolted by that point. Not matter how good he is or what he done in the U-23s his actions between April and July are indefensible. He took the piss and thought he could get away with it. He's learnt the hard way that he can't take shortcuts under Klopp. We let c*nts like Ruddock take the piss under Evans and things untangled pretty quickly. I, for one, am glad that Klopp has taken this action. No one is bigger than the club even if that means some short term pain. Team discipline and application is the key to any successful team. Sakho might have all the ability in the world but he's not shown the consistent application to get the most out of his ability. 6 good games at Crystal Palace doesn't change that fact one little bit.
Again we have a star player who literally put lives in danger, imagine if he had killed someone, how detrimental that would have been not only to the families but to the reputation of the club. Sakho has come out and apologised for his behavior - that's good enough for me.