Funny you say that. I've moved my presentation workflow entirely to HTML5+JS. d3 is amazeballs and should be used at every available instance (and so is raphael)
How much preparation did you put into your templates approximately?
How long does it take you to do a quick one-off?
How long for a professional looking presentation for public speaking?
In presentation to clients, I write reports/presentations per scenario/campaign. I use your bog standard Initializr+Bootstrap, the visualizations have been previsualized on ggplot, and then translated into d3 where it makes sense.
How long does it take? 2 - 5 days per report/preso. Like I said, it mayn't apply to everyone. I have the luxury of time.
I don't usually do the presentation (can't recall when I did one). Speaking in public (even to normal people on a non presenter basis) terrifies me
I'd be interested to see one of your presentations though, in case they're not all confidential. I think your approach might make sense for product launches for example - where it needs to look even more professional than the junk I do. If you're interested I could also send you an example Keynote file if you have a mac, just to see the quality difference.