So, you want 30 fps video played at 30 fps look like the original 60 fps video?
You could try either blending 2 frames together
Code:
YourVideoSource()
Merge(SelectEven(), SelectOdd())
or play around with interpolation. However, I don't think that blending will look that good, really, and I doubt if interpolation is what you're looking for if you apparently already tried playing with Motion Blur and such.
Alternatively, you can also just drop every other frame, but you already mentioned that you don't want that.