I guess for some, but I am on my 3rd play through (I just got the game like 5 or 6 days ago), and I have yet to use firebombs at all honestly, I just sell them for gold. You as the player could choose not to use them for more strategic tactics. Personally I like focusing on positioning, and use of each class in my fights. The mechanic is there for people that want them, and can be ignored by people that don't. So am I missing something?
The problem isn't simply that they're available as a (substitute for) strategy, the problem lies in the ubiquity and the fact that gameplay has been specifically balanced around them being so. Thus, the issue with every goblin having access to multiple surface/status-creating items or every encounter having a significant high ground/low ground (dis)advantage element. It distorts how you approach the game so that if you don't make use of those mechanics, you will either turn combat into a brutal (and unfun) experience for yourself or you'll end up failing an encounter.
Instead of encouraging players to find creative solutions to problems, you'll encourage them to use
those solutions because every alternative is objectively worse.
