The first ARM processor was designed in 1983-1985 to get more performance in Acorn Computers to enable low cost performance computing for the masses, these choices in the ARM design that Sophie Wilson made back then define most of the ARM processors on the market today.
You can also watch Part 1 and Part 2 of my Interview with Sophie Wilson, filmed at the Center for Computing History in Cambridge UK http://www.computinghistory.org.uk/
