I'm sure most of this has been said but:
1. Lots of people use THF, it is in fact optimal for several builds even without epic SoS.
2. The best DPS in the game is currently THF (Epic SoS).
3. When Half-Orcs come out their high STR will push people toward THF builds with them.
4. THF is only worse then TWF for "standard" melee builds at end-game really, make more good THF epic weapons and that discrepancy is solved, it just requires some grinding.
5. In short (that's a lie), having one fighting style be better than another for certain builds is not a problem, nor is one style being more popular a problem. There are lots of things in DDO that are basically useless or very underpowered (turn undead for example), and the game gets along fine without them. THF is certainly more important than turning, and if it was that useless it would be a problem, but it's not that useless, far from it. Minor changes and balances are OK if they are well thought out and necessary (such as changes to reduce lag that keep DPS at basically the same level for all builds HINT HINT), but a complete overhaul should only be done in extreme cases. How can we feel comfortable building toons if you are gonna change things this easily?