The difference between the quality of LD's and NLD's might, I think, lie not in the dreams themselves but in how you remember them.

Dreams are unique in human experience in that they are the only thing we do that can be defined only by memory (except for, I suppose, deeper forms of meditation, which I tend to categorize with dreaming anyway). There is, currently, no way to record your dreams in a meaningful manner -- no cameras, recorders, other witnesses -- so we rely completely on how we remember the dreams when we wake up.

LD's being waking-life consciousness events of, often, some personal import, are vastly easier to remember, often in great detail and as meaningful moments that have already been stored in long-term memory when you wake up. NLD's, on the other hand, are generally discarded by your memory systems as you begin to wake up, so remembering even the most vivid of dreams can be very difficult. Also, during NLD's, DC-you is assuming everything is real, so it takes no time to admire the details and vividness of the world they navigate (the same sort of thing happens in waking-life too, BTW); in other words, there maye be literally nothing impressive to you during a NLD, even though the same stuff would amaze you when lucid.

So there is a chance that NLD's are every bit as vivid and awesome as LD's, but thanks to the fact that they are handled upon waking by memory in a way that reduces their imagery to a fog of nearly unretrievable imagery, and they were initially experienced by a DC-you that really didn't give a crap at the time, upon waking they are immediately remembered to be dull productions, when remembered at all.

It all lies in memory and in the nature of your presence in the dream when lucid, and not in the quality of the dreams themselves.