The 14 bullet points with they key messages you want to give in a presentation is not a summary slide, it is the entire presentation.
- Those 14 points are not messages, they are pieces of content, story elements. A presentation usually has 2-3 big points that qualify as messages
- Nobody can remember 14 things
- If you cram 14 points on a summary page, you have to write them down in a way that is too short, too generic, too vague (= not interesting)
- If you discuss 14 points on a summary page, you have to spend too much time on each of them to explain things
What to do? Use the summary page to set the stage of your presentation, give a hint at an interesting, counter-intuitive, surprising conclusion, and say what it is you actually want. Then dive into the 14 story elements one by one, slide for slide, without summarising them beforehand.
So, the mistake of the 14 bullet point slide, is not the slide design. (The correct summary slide might actually consist of 3 bullet points), The mistake is the way you structured the presentation.