I share some of your concerns regarding exposure, or lack thereof, to actual competition for this class. I've been a big fan of these players for years - Green, Cunningham, Kuminga, and Williams have all been long-term favourites of mine.
However, I'm not sure there's a need to run away from this draft or anything. We've got Daniel Theis, Jeff Teague and Semi Ojeleye coming off the books this off-season. Theis will probably demand more money than we're willing to offer him given the addition of Tristan Thompson and the ascendance of Robert Williams. We should also look to add a 3rd string guard to replace Teague. Not sure if Semi will stick around, but if he doesn't I wouldn't lose any sleep over it.
So that leaves us with 3 holes in our roster. 3rd string guard, 3rd string big and a general bench forward. Given we have 3 picks in this upcoming draft, I would like to see us use them all. Kemba, Brown, Tatum, Smart and Thompson are a good collection of veterans. We have some solid young talent in Pritchard, Langford and Nesmith, and adding a few guys to that would be great IMO. I am pretty high on Yam Madar, and think he could be a potential guy to come over next year and play as our 3rd string PG. But if he doesn't, we should look at another NBA-ready guy.
Throw in the potential addition of someone with the TPE (Harrison Barnes, Aaron Gordon, Terrence Ross, etc.) an
If we can leave the draft with Luka Garza (skilled physical big at the end of 2nd round), David Johnson (versatile combo guard with size at the end of the first - early 2nd) and Aaron Henry (defensive specialist wing in the 2nd round) I would be ecstatic.
Throw in the potential addition of someone with the TPE (Harrison Barnes, Aaron Gordon, Terrence Ross, etc.) and our rotation next year could look like:
Kemba Walker / Payton Pritchard / David Johnson
Marcus Smart / Romeo Langford / Carsen Edwards
Jaylen Brown / Aaron Nesmith / Aaron Henry
Jayson Tatum / Harrison Barnes / Grant Williams
Robert Williams / Tristan Thompson / Luka Garza
That would be a fantastic result in my opinion. This draft, given we have no top picks and no realistic avenue to a top pick (barring a crazy trade) would be a good one to target proven upper-age prospects. Guys like PP last year have shown the merit to doing this, especially if you get the character assessment right. I think Garza fits this bill to a tee, as does Henry and to an extent Johnson.
While I do agree with you to an extent, particularly about the top prospects, I think there is still plenty to be added to this team from the upcoming draft.