Typography designers design a bold variety of a font as if it were a completely new type face. There is no magic computer algorithm that turns a regular font into a bold one. From scratch, designers need to make the call about balance and readability all over again.
I think bold fonts do not look as good as regular ones. They are often bulky and lacking elegance. Italics/bold fonts are usually even worse.
What to do as a presentation designer? Design your slide without bold fonts initially, and only add bold as a last resort. Your first tool of emphasis should be to increase the size of the font/
- To highlight a single word, rather than inflating a whole sentence
- To give more contrast to text written over an image as a background
- To highlight a label in 10pt font or smaller in a complex diagram such as an IT system architecture
(Not) surprisingly, I find that regular slide titles look better than bold ones. Adjust your template if you can.
Somewhat related, a post on color as a last resort.