If you don't want an LLM to write the words, surely you also want to decide on the data and graphs to show by yourself? Isn't that 90% of a presentation? The "looking nice" part doesn't matter as much, it could be black text on a white background and it would be fine.

The important part is the presentation matching your presenting cadence, which is something LLM generated presentations never get right. I don't have a problem with people generating presentations, but most of the time they just end up reading whatever is on the screen when presenting.