Something I find lacking in Guild Wars 2 is the absence of single-target abilities that you can use on allies.
I understand they wanted to avoid the whole tank and healer, and looking at the UI, but I feel like this really takes a lot of activity away between players. There are also abilities like the guardians Merciful Intervention (http://wiki.guildwars2.com/wiki/Merciful_Intervention) which affect only 1 ally, yet you cannot target who it affects. It would be nice if there was at least an option to choose who you target, and if you have an enemy or no one targeted then it would automatically target the lowest health ally. Also, this ability teleports you to an ally and being able to use it for that purpose alone would open a lot more potential for such a skill.