Ether 5: Witnesses on Trial

Here we arrive upon a short six-verse chapter that seems to center on the concept of the future three witnesses to the gold plates.  Verse 3 seems to be the central point:

And in the mouth of three witnesses shall these things be established; and the testimony of three, and this work, in the which shall be shown forth the power of God and also his word, of which the Father, and the Son, and the Holy Ghost bear record—and all this shall stand as a testimony against the world at the last day.

It seems to me that this scripture is grossly overestimating the impact of the three witnesses.  It also seems to be grossly overestimating the visibility of God's power.  There have been a few events in which a divine power has apparently favored the organization that arose from the fruits of "this work" and the "testimony of three," but all those events are now historical.  The mass healing of the sick in Nauvoo and the miraculous eradication of the insect problem in the Salt Lake valley are both great stories, but they're old and difficult to verify.  Surely if the Church of Jesus Christ of Latter-day Saints is the same church founded upon the same principles to which these three witnesses were dedicated then the power of God would have continued to be shown forth throughout its history.  Surely there would be some miraculous event favoring the LDS people that I could point to in my own lifetime.  Right?

I made a similar point once in an email to my sister.  She had been trying to get me to reconsider my lack of faith and made mention of miracles as reasons to believe.  I jumped on that in my response and asked her why public, theatrical miracles like those in the scriptures no longer take place. Nobody is feeding five thousand people with a few loaves and a few fishes anymore and no brave missionaries are bringing entire prisons down to rubble around them.  Her response was that miracles don't have to be like that.  She pointed to the fall of the USSR as a modern miracle because it was unexpected and beneficial to mankind.  I don't particularly buy it in that context, but with this chapter in mind, the end of Soviet Russia certainly would not classify as an extension of the three witnesses.  If that's the only miracle we can come up with, where is the power of God that's supposed to be standing as a testament of the gospel in the last days?

Also, why were the subsequent eight witnesses necessary?  According to Ether, which makes no prophecy about numbers four through eleven, three witnesses should have been plenty.