Yes, it can be extended to 5 meters... by spending a Talent. Isn't that what Talents are for? You spend points on them to get a special bonus.
You get a special bonus, which should have a sense. Right?
Does it make a sense to make a skill "Long fangs" so its extends daggers range to 6m?
You get a special bonus which should be a special, touching spells are special by themselves. They should be dangerous for the target and for the caster to come to close. That is tradeoff to consider. Give them a range so make it a common.
Touch spells should have same range as daggers.