GW2 has 10 fixed slots with the first 5 flipping depending on your weapon load out. Your first 5 skills may be changing between defensive to aoe to single target in the middle of a battle making it difficult to always have a particular key associated with a set role.
I fear you may have to just get used to a new system here. I have a similar experience where I try and have a universal set of keys across all chars/games. I got used to GW2 pretty quickly though.