How would this be done today with updated knowledge/technology?
My $0.02 opinion is that the slab should be constructed to prevent as much water infiltration as possible. Joints should be properly spaced to allow for initial shrinkage during concrete curing, and subsequent heating/cooling movement. This would minimize random, unplanned cracking.
The joints MUST be properly sealed. And then the joints MUST be inspected for sealant deterioration and promptly repaired.
Whether this can be done to a sufficient degree to make a drainage system unnecessary, I don’t know.
I'm assuming you're asking about the drains...
The FRpost link below provides modern design technology based on spillway design history and failure knowledge gained. Oroville's main flaw was in designing the drain "within" the slab, thus forming thinning zones (and severe slab cracking in the drain pipe zones). Aggravating this was that the slab design had no bottom rebar reinforcement, which affected the flexure resistance. Modern designs incorporate a superior "water stop" system to minimize water penetration at the expansion joint seams of the concrete slabs. What is not shown in the FRpost modern design drawing is the same type of downslope "collector" drains. This would be the same as done in the Oroville design (gravity flow collectors to sidewall outlet drains).
note: the worst case 40% thinning reference has been found to be up to 60% thinning due to the bell coupling dimensions + the 6" VCP pipe upsizing from the original spec 4" VCP pipe blueprint drawings. The Board Of Consultants have confirmed the "thinning" problem (but did not go into further specifics - likely a hot topic structural design flaw if revealed to the press/public).