word and publisher probably don't do anything complicated enough to warrant a powerful PC, but Excel spreadsheets can get big enough where you need lots of ram and CPU speed to search through them/process your formulas.
Simple applications by default already have their needs met by the low power hardware you can find in cell phones for example.
Only insanely huge word documents (like legal briefings) or publisher files (a big complicated webpage) would benefit from just having more ram so they can store more of the files in active data.