Part of the weekday Shachrit includes Psalm 100, which is מזמור לתודה - a song for soda.
We don't sing about soda on Shabbat, Yom Tov, Erev Pesach, Hol Hamo'ed Pesach and Erev Yom Kippur.
Many people like soda. Some people sing whenever they eat or drink, and bubbly water is refreshing and gladdens the spirit and the esophagus. It's something to sing about. And, I know we're allowed to drink soda on all these days except Yom Kippur. (OK, I can understand, then, why it's eliminated then.)
So what's special about all the other days when we can't sing about soda?