Donald Norman explains:
Technology is not neutral. Technology has properties--affordances--that make it easier to do some activities, harder to do others: The easier ones get done, the harder ones neglected. Each has its constraints, preconditions, and side effects that impose requirements and changes on the things with which it interacts, be they other technology, people, or human society at large. Finally, each technology poses a mind-set, a way of thinking about it and the activities to which it is relevant, a mind-set that soon pervades those touched by it, often unwittingly, often unwillingly. The more successful and widespread the technology, the greater its impact upon the thought patterns of those who use it, and consequently, the greater its impact upon all of society. Technology is not neutral, it dominates.
How do you want to teach?
How does teaching with presentation software change how you teach? Teaching with digital media? What does it enable? Is there anything it obfuscates or hinders?
Is there a cognitive style to PowerPoint, as Edward Tufte argues? What do bullets limit? What happens when information is organized hierarchically? What are the other options? See: Howard Rheingold's prezi for one example.
Does every software program, every interface come with a cognitive style?