So soon on the heels of IBM's 100th anniversary, I read this news item:
http://www.reghardware.com/2011/07/29/ibm_selectric_golfball_anniversary/Sunday, July 31 will be the 50th anniversary of the IBM Selectric!
Of course, one can go back long before 1961... all the way back to 1895... and find the Blickensderfer... but I know that a Varityper, based on the Hammond, needed one to press very forcefully on the keys to make it work, and so there were reasons why the Selectric succeeded where the Blickensderfer went by the wayside.
First, you need a good typewriter - easy to type on, producing copy of high quality. The ability to type a diversity of characters is just gravy - a nice extra, but not attractive enough to get people to use a typewriter that works less well than an ordinary typebar office typewriter. (And, to make things worse, unlike the Hammond, the Blickensderfer, which came first, had a non-QWERTY keyboard.)