It can be an incredible hassle to view a PowerPoint file on a Mac without Microsoft Office or iWork. In fact, there doesn’t seem to be any modern viewer application. The only solution I’ve found thus far is to use NeoOffice, which is as slow as heck. And then there’s the added problem if the file is in the new Office format, .pptx. Then it has to be converted to .ppt by some other means before it can be viewed in NeoOffice. Oh, and did I mention how incredibly slow NeoOffice is? It’s really overkill for just wanting to view a file.
So, Preview is used for viewing documents. Why not add support for PowerPoint files into it? I realise that one of the driving points of Preview is that it’s so lightweight and fast, but I doubt adding in support for PowerPoint would compromise this. It could even convert it to some viewable intermediate file like it does to PostScript files if it would help.