Many older languages evaluated expressions left to right. For assemblers this saves you from managing intermediate values and you can spit out ALU instructions in order without need for register assignment magic.
VisiCalc [1], the first spreadsheet program and the "killer app" for business on the Apple II, also used left-to-right evaluation. Dan Bricklin said he needed people to be able to quickly enter equations as they did on a cheap (non-RPN) calculator [2, at around 35:10].
