Should hybrids be produced? If yes, when and why.
I think this question should be modified or made more specific:
"Should hybrids be produced by hobbyists? If yes, when and why."
To this question I vote "NO" (the reasons for which have been outlines very well in this thread and other threads). With the advent of TWI and Frog tracks the odds of non-labeled hybrids being incorporated into existing representative captive populations of frogs is greatly reduced (but still not impossible).
on the other side of the issue:
"Should hybrids be produced for scientific gains that may benefit humans, frogs, or other organisms? If yes, when and why"
All of our food crops represent hybrids across lines, populations, and even species. "lines" of laboratory animals (flies/mice/rats/etc) are often produced for better scientific research.
A hypothetical example that is also not an inconceivable possibility:
A frog is found to produce and amazing that will send a particularly common cancer into complete remission. Unfortunately there is no known way to synthesize this drug, the only way to get it is to extract it from the frogs. The frogs are raised in captivity in large numbers but still the drug is only produced in a small amount for frog, thousands of frogs are produced just to get enough drug to save one person. Some frog researchers find another species that produces a similar chemical that has no effect on cancer but is produced by this other species at levels 10000 times that of the one that produces the active drug. In this case hybridization and selective breeding, couple with other genetic tools could be used to breed frogs that produce as much of the drug as possible per frog. In the long run this may not be the ideal way to produce the drug but will save thousands of lives while alternative production means are researched.
Read up on the production and history of Taxol: