I completely disagree with the
Wrong... it many cases it is VERY important to backup dropbox (or similar cloud apps) manually and move them to a new machine. In my case, my company uses Dropbox and syncs this data to SharePoint. 90% of the user's data is within Dropbox. Some users even have 30-50 GBs worth of data in this cloud sync location. When you migrate them to a new machine, and they are at a client site working, do you really expect them to wait for 30-50 GBs of data to download on a shared crappy wifi connection or a mobile hotspot (that will eat up all of their data and charge them several hundred dollars). Even if at their house, do they really need to wait for that much data to download before their machine is fully functional again?
I would hate to see the computer tech that failed to migrate this data with the attitude of "The whole point of Dropbox, Google Drive, etc is that the files are on the cloud. You reinstall the software and let it redownload, NEXT" seriously hinder a users ability to use the machine when it is returned to them! Even worse, get a follow up reverse bill from your client because you just ate up their data cap and cost them several hundred dollars in data overages.
In the end, it takes an extra hour or two to move this data for them. Not completing this action could cost them days of downloading this data and a huge loss of their time. Once on the new machine, it simply does a data check to make sure it is correct.