Why are there no Green Steel Bastard Swords?

[gpk]

And, so what... You do a few % less DPS. You (or the caster behind you :-) might die an extra time every couple of weeks... Meh...

That's untrue, it's much more than just few % less.
Take a self gird no rage human ftr with gr weapon spec w/ 32 str, mineral 2 Khopesh would beat a 2d6 base BS by ~15% average per swing.
A 17x3 is a lot more powerful in nearly all scenarios than a 17x2, the multiplier multiples strength, weapon spec, bard songs etc.
A same khopesh will always beat a same BS on crittable mobs, and the more buffs and feats you throw into the mix the wider the gap. Typically it can be 10-15%, not like 1-5%, 10-15% is a lot in DDO.

In fact a less-good khop can often match a "better" BS, and now with crafting it's not even a contest anymore.