People just don't spend time on presentations and things will go wrong.
If you copy/paste while creating presentation you'll end up with differences. Vector graphics is nice, but try getting that working nicely while copy/pasting from various programs.
E.g. creating a control chart in some program (forgot the name, need to check @ work). You can paste but by default it just pastes an image. Even as vector it'll look off: different fonts, colours, etc.
I don't really see a presentation program fixing arbitrary copy/paste things.