Is 9mm enough? I dunno. But it was designed to knock down 180lb men, not big honking bears.
What does it matter what the design intent was? Design intent often does not turn out to be the only reality for a product and is often a failure. Viagra was a failed blood pressure medicine. Kevlar was designed with the intent to replace steel inside of tires. Carrier's air conditioner was originally designed as a dehumidifier, not something for cooling purposes. There is ammo out there that is designed for varmint that works very well in much larger game. There is expanding ammo out there that does a poor job of expanding reliably. In the grand scheme, design intent is meaningless. All that matters is how the product actually performs.
I would like to point out that it isn't power alone, nor bullet shape when it comes to penetrating a black bear's skull. The angle matters, as well.
Few would argue that a .30-30 doesn't have the power, especially at close range, but I know of a case where several (4) shots deflected off a bear skull at close range. Shot 5 at a slightly different angle penetrated ending the bear.
I see and hear of claims of bullets deflecting off of animal skulls all the time, including bears, but the evidence for this actually happening is often lacking. Particularly in the case of bears, what folks often see as the bear head is a LOT of fur surrounding a much smaller actual skull. From what I have seen as examples on YouTube appear to be misses more than deflections or "bounces." Nobody wants to admit they missed.
I made this dotted representation of the bony area (skull and jaw) of a bear relative to fur. As can be seen, the bony area is much smaller than the perceived head size.
https://thefiringline.com/forums/attachment.php?attachmentid=40315&d=1230728059 On top of that, an even much smaller area is brain/brain stem, which are the critical areas that need to be damaged.
Here is a classic video, hog and not bear, where the claim is that the bullets are bouncing off the hog's skull. The guy is actually missing and shooting the ground. However, this sort of claim seems to be typical.
https://www.youtube.com/watch?v=rI0l29YGA-c
Bullets certainly can deflect off of curved surfaces, no doubt. So the potential is real for this happening, but I doubt it happens as commonly as claimed. However, if there is a nice picture of 4 stripes of where bullets literally deflected off the skull (and there would be actual skin and hair removed as a result), that would be super cool to see.