I also think that adding these missing skills would be a great idea! This could also be a great tool for Anet to make the core classes more attractive compared to elite specs, which is what they have been trying to do with the latest balance patches (core death shroud changes and thief traps rework as an example). It would also be a great way to give some new content to everyone playing the game, regardless of what expansions they own. And for revenant I also think adding a new skill per legend is more realistic than adding a new legend, as there won't be any trait line supporting a newly added legend.