They look like they would work if you just dropped the bike at a stand still, and that would have to be an easy drop. But if you were moving I don't think they would be much good.
I think if the bike is placed carefully down, it will prevent contact with the bags. But if you walked over to the bike and pushed it over, it bet it would have enough energy to bounce enough (or even cantilever over) and hit the bags. Besides, all this assumes working on a PERFECTLY FLAT and CLEAN paved area with no obstructions, holes, large rocks, curbs, etc.
Compared with no protection at all, I think they would certainly help tremendously even with a harder fall over or with a moving fall. Plus they really look nice (unlike most protective stuff). They are certainly expensive, and not as easy to obtain as other stuff, though.