Does this have anything to do with the fact that Ran is involved with Cabot Links and is now taking a closer "look" at this feature?
"Where drainage is not a problem, does a course with nothing but elevated tees reflect a weakness in the design ?"
No in the context that you stated with respect to drainage, IMO, but I do think it reflects an aesthetic weakness and certainly an artificial look that isn't necessary.
On their own whether drainage is involved or not I think Doug has made some good points.
"If the golfer was afforded a view of all the hazards on a particular hole from the teebox, so what? They still have to execute. For 99% of golfers, isn't execution the problem?"
For the most part and though a view does make you feel better about what lies in front of you, it really does come down to good execution for most golfers.
"If elevating the tees rendered some or all of the hazards useless, then I would say yes, it would be a weakness of design."
I am not sure how this condition could exist as execution along with all the other environmental conditions, wind, maintenance.... again enters the picture and an elevated tee really doesn't change the relationship between the golfer and the hazard, or the elements that Nature and the architect present. If for example, and we have all seen this many times, a hole starts on a high rise in the landscape, really high I mean, and we find an elevated tee built in that location, for no apparent good reason, the elevated tee in question affords no further advantage, the golfer can see the hazards with or without the elevated position, or as Pat asks, does this tee render the hole weak? I don't believe so, IMO.