See also: My Guild Wars Suggestions and Grievances
Do away with dedicated healer roles entirely
The problem: Dedicated healer roles make sense in theory for RPG gameplay (just as dedicated Tank roles do), but I believe they have only dragged down the gameplay in practice. While a dedicated tank, or interrupter, or nuker isn't always required for PVP or PVE gameplay, a dedicated healer is, with very few exceptions. This has created an obsessive and elitist reliance on Monks in all aspects of Guild Wars gameplay. To make matters worse, Guild Wars monks have always had the capacity to almost instantly heal a teammate to full health. The response to this power that monks currently wield is that players/enemies must often focus their attacks on the monks first, often completely ignoring the other 6 or so players in the opposing team.
The solution: Rather than having dedicated healer classes, all character classes need to have the capacity to heal themselves. Additionally, all character classes need to have the capacity to offer limited healing/protection capabilities to their teammates.
The result: Less dependence and reliance on dedicated-healer character classes/professions. This places a greater emphasis on individual builds, in which each player is responsible for keeping him/herself alive - while still having the versatility to offer limited heals and protection to teammates.
Possible drawbacks and conclusion: Change. People are oddly afraid of change. Even though we look forward to the many changes that GW2 will bring, I believe that some people would be unwilling to let go of the concept of dedicated healers, despite the many game elements that would be brought into balance without them. Keep in mind that, because each character class would have the capacity to heal/protect self and party, you could still create a dedicated healer with the proper skill selections. But creating an entire class dedicated to healing, when each character ought to be able to do it by his/herself, only bogs the meta.