Basically problems like these are an issue in any new edition. The core rules only handle the "main" archetypes, and splatbooks fill in the gaps. You saw this in 3e with more throwing feats and throwing based Prcs.
For now I would recommend this feat to your DM
Master Thrower (Heroic)
Benefit: When using a power that has the ranged weapon keyword, you may instead use a throwing weapon. If you use a heavy thrown weapon, you can use your strength for the attack and damage rolls.
I don't think this feat would be imbalanced in the slightest because thrown weapons do less damage and have shorter range.
For now I would recommend this feat to your DM
Master Thrower (Heroic)
Benefit: When using a power that has the ranged weapon keyword, you may instead use a throwing weapon. If you use a heavy thrown weapon, you can use your strength for the attack and damage rolls.
I don't think this feat would be imbalanced in the slightest because thrown weapons do less damage and have shorter range.