This is a really minor point, and there are more serious issues regarding these enhancements.
As you seem to know, ranged attacks in DDO are weak, unless prehaps you are an actual ranger. Allowing someone to qualify for Warchanter with Weapon Focus Thrown would be largely irrelevant. Turbine may as well allow it, because it's an underpowered choice and it would be almost a self-nerf for a bard to take that feat.
The important issues are the number of feats required to qualify for these things. Mainly, the problem is that since all bards take Extend Spell for longer Haste, Spellsinger has no real cost in feats. But since few bards have both Power Attack and Weapon Focus (and most have neither), Warchanter practically has a cost of 2 feats.
It looks very unfair for one option to cost 2 feats while the others cost zero.
Warchanter should be changed to allow you entry as long as you have spent one feat to demonstrate your dedication to aggressive weapon combat. Anyone with ONE of Power Attack, Weapon Focus (any), TWF, or Point Blank Shot should be allowed to qualify.