Talk:Cross
"As an interesting side note, it didn't fall completely out of favor until the mid-20th century. The Kirtland temple has a cross on top." -Exmormon.org
---
http://www.bycommonconsent.com/2006/11/exasperation-with-the-media/#comment-82881
My understanding is that is was in vogue for Restorationist movements in the 19th century to eschew the use of crosses as symbols in order to differentiate themselves from established Protestant demominations. Other churches that arose during that time period, such as the Jehovah’s Witnesses and some of the Churches of Christ, also avoid using crosses.
Therefore, I think that we don’t use the cross today out of pure force of habit and the various justifications for it (i.e. we don’t think the atoning event occured on the cross, etc.) are simply later rationalizations for the tradition. Changing that policy today would call into question the various rationalizations and perhaps undermine the tradition adopted by the early church leaders (i.e. to break from traditional protestantism) even if that tradition has less meaning today.