That's because your car can run on any brand of petrol, your radio can pick up any channel, your CD player can play any CD.
If each book publisher wrote in their own made up language, who would learn more than one?
MSOffice is a development system to some programmers.
/full/ implementation of modern standards and formats such as PDF: you're basically going to choose Adobe's program, or the open source version ports. Does running !PDF on ROS 5 give you path clipping?
Flash: well the spec is open, but as Macromedia do a free linux version noone's bothered to make an open source version of the latest specs
CSS: Noone does full CSS, NetSurf does quite well.
Excel: Not a standard. Someone should use the OpenOffice loader or something