There are wizards in novels who can heal. As I recall, both Goblin and One Eye in the Black Company novels had some minor healing abilities.
In my former campaign, there was a prestige class which gave a wizard some access to healing magic. (The PrC was tied to worship of a group of gods of magic and knowledge.Compared with many of the PrCs out there, I do not believe having some access to healing magic was too unreasonable.) While I do not have Arcana Unearthed or Unearthed Arcana yet, it seems that both blur some of the lines between arcane and divine magic. I do not see this as too powerful of a sacred cow, as there are already enough fantasy conventions to challenge it.
Perhaps if one allows arcane casters to have some access to healing, it might be wise to ensure that divine casters are still better at healing. So, a wizard with access to healing magic might only do the base healing amount (1d8 for a cure spell) and cannot swap out spells for a cure spell. Also, if you go the Prestige Class route, something is usually lost for something gained. (For example, in many prestige classes for arcane spell casters, feat progression or familiar improvement often suffers. I would perhaps have preferred making familiars a possible choice for sorcerors and wizards as they do not always fit the style of some characters.)