Materials to craft 10 bombs are too high and bombs cannot be crafted at basic workbench like the description says.
Yes. You are correct.
They are not powerful at all, period.
They fall off a cliff by level 4, you mostly use them in the beach to deal with the bomb throwers and early groups of mobs, and then forget they exist because their damage scales so abominably for later levels.
I get why they did it, to avoid abusing bombs to trivially wipe out groups, but they could have added much better utility instead to bombs.
Regular bombs could fill enemy poise meters with high native stagger to use as a crowd control tool, and the elemental types could do slighly lower poise but apply significant if not full build up of their element to enemies.
They could also have effects like applying blind on enemies so they miss their next few attacks, or weaken enemies so they do less damage or afflict them with a 30% slow, etc. Basically, strong debuffing tools.
The other problem is the materials to craft the bombs. No way anyone is sacrificing incredibly rare gems just to craft a consumable you only get to use once when there are tons of respawning enemies.
Same for oils requiring fish. Fish is non-negotiable, fish food provides focus and is so much higher impact than a weapon oil that only lasts a minute.