One of the stated aims of the changes to resource management was to prevent skill spamming. As the changes leave the majority of skill spam specs unaffected, while seriously hampering specs not based on spamming, I propose a better solution.
Multiple successive uses of the same skill increase the cost, effectively, the skill gets a cost debuff, with no time limit, increasing with successive uses. You can earn this debuff off by using other skills (not necessarily on a one for one basis, dependent on the skill) . All cost debuffs are removed when combat ends.
For taunt skills, used against a currently untaunted target, no cost debuff gets applied, but does for currently taunted targets.
Similarly, healing skills (ie that target friendly targets only) don't get the debuff if those healed are below a % health (say 60% - 75%).
This would make skill rotation highly advantageous, would enable tanks and healers to use role critical skills unaffected, if used in a strategic way, and make all spam specs far less viable.