What I never understood about the witness view was how they became so prejudiced against the traditional cross that they began to view it as a "pagan symbol" and practically more Satanic than a witches pentagram. This was quite some time after they openly used the cross themselves, ironically during their self-proclaimed "selection" as the only true christian organization left on earth.
And yet, they insist on the upright stake, and openly illustrate it in their literature - which stake was itself pagan in the sense that it was not Jewish.
Seems like they copied a lot of this from the rantings of Alexander Hislop and have, as others pointed out above, simply been nursing a grudge against other christian religions as per their usual custom.
So much simpler to just say "we don't know for sure". After all, they don't know for sure that the name Jehovah is halfway right, but accept earlier christian tradition prior to their own time for the spelling and pronunciation on that all-important name.
Their explanation on Jehovah is that "it is commonly recognized now after many years and is good enough even if it is probably wrong". Why wouldn't that explanation equally apply to the traditional christian cross?