Just because there's precedent doesn't mean that such a request is going to go over well. I don't think that Iguodala ever struck me as a me-first ego guy. Monk, for what it's worth, does.
I don't think that the bold is necessarily true for me-first ego guys. I'm not going to tell you LeBron or Durant or Kobe or Jordan have ever held winning as a secondary objective, but I would also say that all of them were me-first ego guys, in the sense that I can't even fathom one of them in the prime of their career accepting a move to the bench for the best of the team. Yes, yes, those guys are a tier above the players we're talking about on our team (specifically Monk, DeRozan, LaVine), but what I'm saying that there is a certain level of player who is good enough to start and who wouldn't imagine moving to the bench for the good of the team, but who nonetheless "puts winning first". They just think that moving to the bench can't help winning.
As our cards got dealt, we ended up with three of those guys who basically all play the same position and are all kinda bad at defense. And you're going to have your posters who are going to raise a hue and cry about how bad our GM was to get into this situation, but that's not me, because I see the road that brought us here, and I have at least some understanding of the difficulty of getting players to Sacramento in the first place, and I understand that for a team like Sacramento, it is a better strategy to maximize assets and address balance later - once a Sacramento lets an asset slip in order to improve "balance", that asset is gone and may prove very very difficult to replace. This is why it was smart to draft Hali even though we had Fox. Could they play together? No, not really. But we grabbed the asset that didn't fit, and then adjusted later - using the asset. If we passed on Hali because he was a bad fit, we never, ever get Sabonis.
So, was it at least a bit of playing with fire to re-sign Monk? Maybe a bit, because we knew he would eventually want to start - I'm pretty sure he already wanted to start. But if we let that asset walk for nothing, we lose that asset. And, hey, the roster fit wasn't as bad (though it wasn't great because as a 2 Monk gives up a lot of size) as it became, and, hey, he was close with Fox. Keeping Fox happy was the priority (we didn't know that was impossible).
Was DeRozan an ideal fit? No, but he was an available player, and a pretty big asset upgrade from Barnes. And still, you can squint and make it work. Is Fox (1), Monk (1/2), DeRozan (2/3) a bit of a squeeze if you want to find minutes for a defensive specialist like Ellis? Sure. But again, Ellis is still not as big of an asset as any of those three dudes. So now we have post-Hali-trade, where we had one guard "asset" to this point, where we have three guard "assets". You don't say "no" to that just because the fit is awkward, because you're adding assets, and you can fix it later.
Now...is LaVine an ideal fit? No! But he is an asset, and we apparently had the option of losing Fox for no assets, or losing Fox and getting a bad-fit asset back. Again, from this point of view, it's a no-brainer. Do we have to fix it in the offseason? Almost certainly. Unless somehow we go back to Sabonis running the offense out of the high post and things click hard, yeah, at least one of Monk/DeRozan/LaVine has to go, hopefully in favor of a better-fitting asset. For instance, it would be nice to have a true PG. It would be nice to have a full-sized wing. But you don't get there by passing on assets, or letting assets walk, and then building from scratch. Maybe you can do that in L.A., where assets come knocking at your door and you have to pick between them. But not here.