I think the gameplan is more obvious than is being given credit here. Let's remember this was a terrible team last year, and our one real addition was hurt through training camp and preseason. This was always going to be a bad team this year. Once you accept that part, the gameplan kind of writes itself.
The team NEEDS to figure out if Hayes can become something useful. That's why he's starting. That's why we're trying to use him as a true PG. His passing is a legitimate NBA skill, but he HAS to develop some ability to finish his drives or shoot. And to do that, he needs minutes.
Cade is still working himself into form. Obviously this last game was good, but we shouldn't expect 50% shooting and 45% from three to suddenly be his new normal. He's still very much figuring out the NBA game (just look at his abyssmal finishing and FTAs to see an obvious area of improvement), and taking some ballhandling duties off his hands (again, forcing Hayes to do something) is a smart plan. Let him figure things out, and increase his time on the ball as the year goes on (and potentially as faith in Hayes wanes).
Bey showed last year he can be a fine 3 and D player. But since the team is terrible no matter what, it makes sense to let him try to expand his role and see if he can handle more responsibility. He's taking a lot more shots this year, a lot more that he's expected to create himself, and his numbers overall reflect his struggles. It would be nice if he kept his 3pt % up, but that's also a weakness of the team. Check out the starting lineups from every game this year (or the whole team for that matter). There are really no shooters. It's not surprising that the one guy who CAN be a good shooter might get more defensive attention on the perimeter.
Honestly, the rest of the team only maybe matters. Grant is a volume scorer, whose best role is as a 3rd or 4th option on a good team. Stewart NEEDS to develop a perimeter game if he's ever going to be more than a hustle-guy. Losing a ton of games this year and landing another top pick has way more value to this team than trying to squeeze the best possible lineup out of the team today.