So, by altering the spelling of God in written form is showing honor. Would one then show the same honor when speaking the word by saying "Gee (G) dash (-) dee (d)" as in "Oh my Gee dash dee" ?
Many Christians thought so at one time, apparently:
All ways to avoid taking the Lord's name in vain.
However, as I understand it, the custom of omitting the "o" from the name of God is not just to show respect but to prevent a (witting or unwitting) third party from showing disrespect. Spoken speech is not a permanent form and can't be defaced.