Despite Google confirming that they do not use the keywords metatag for ranking purposes, the keyword meta tag is not completely without it’s uses.
When you optimise the content of a page for a given set of keywords then that is an investment you have made, and the resultant set of keywords is an asset. The keywords meta tag is a simple way of safe-guarding that asset over time.
More often than not, web pages are optimised when they are initially published. Subsequent edits and updates are unlikely to include a recheck against the original set of keywords especially given the web publishing models many organisations use. This means that the original investment has been at best devalued and at worst wasted.
My recommendation is to keep entering the keywords into the keyword meta tag that the page has been optimised for – not because Google cares about it – but so that editors can be educated to always check their content changes against that list, and to update the list when the page has been re-optimised.
By utilising the tag in this was, we increase the return on the original investment that was made in optimising, and increase the chance that future edits will also be on target & keep the original keywords in mind.