That makes sense for some lenses. Have you seen the hood for the 16-35L, TS-E 24L, etc.? Not a whole lot of protection there...
I'm actually shooting right this very moment with the 24.
I'll agree that there's not a huge amount of protection. However, I'd also argue that it's more than enough to keep a photographer from accidentally touching the front element, especially since this is a lens that'll rarely be used off a tripod.
The 16-35, even when hooded, I can see being prone to the fingerprints of curious children. And I could see it being less effective for protecting the lens if you're wildly and randomly swinging it around at the end of the strap. But, obviously, the answer is either to supplement the hood with a filter if you're going to be handing the camera to curious children or randomly swinging it around at the end of the strap...or to keep your equipment out of the hands of children and to pay a bit more attention to how you're handling it.
But both hoods will protect the lens against damage from being dropped far more than any filter ever would.
Of course, the ultimate example of a worse-than-useless hood would be the one that comes with the 8-15. Of course, that lens only takes rear filters, so it's not like you have much choice but to be careful. Personally, I'm just treating the hood of that lens as an extension of the lens cap, and may well tape the two together.
But, still. 99 44/100% of lenses are adequately protected against most likely causes of damage by using a hood. One should be aware of the exceptions, yes, but one also shouldn't let perfection terrorize the good. And, save for the hood of the 8-15, a hood is never going to degrade image quality and will almost always improve it, often significantly so.
Really, the default position should overwhelmingly be, "Use a hood." Filters can be useful, and one should know when they are. But filters are the exception; hoods are the rule.