Why Type 1?
Using Type 1 offers the following benefits:
Type 1 format files are smaller. Usually about half the size of TrueType, Type 1 files take up less room on your computer's hard disk.
Type 1 offers the greatest selection. Over 30,000 Type 1 faces are available today in a variety of price ranges for most computer platforms. Type 1 is the format recognized by hundreds of models of PostScript printers sold by dozens of manufacturers.
Type 1 documents are portable. Type 1 is available on virtually every computer platform from microcomputers to mainframes. Documents created on one platform can be moved to any of the others with little effort. TrueType is only available on Macintosh(R) and Windows(TM) systems.
Type 1 is the only recognized international standard. It's available on virtually every computer platform, preferred by professional computer graphic designers and required by typesetting service bureaus.
Very few TrueType fonts offer expert sets, old style figures, small caps, ligatures, and other variations required for professional typography.