On my MBP, Word and Excel take absolutely forever to launch. Every other app comes up instantly and if my workflow required using these apps all the time, I'd be really annoyed by having to turn them off and on constantly. I keep my normally used apps (Chrome, Outlook, Sublime Text, iTerm, Slack) running all the time since those are part of my workflow and would be annoyed if they were constantly crashing.
That hasn't been my experience with Word 2011 or Powerpoint 2011. (I do not use Excel) They startup almost instantly. I do know there is a big difference in startup times if you're using Word 2016 or Excel 2016. Office 2016 is scattered all over the place with separate font folders and associated files.