ICE makes people more thirtsty as the drink is lower liquid volume value in the same cup....
As it Fills up the cup with less drink. so they are more thirsty than when not having ice in it...
This is used in real life, the more ice the worse value the drink is in real life...
So Yes adding items reduces the drink volume value of the cup so people get even less value from the drink... Volume of the ice removes the core drink product... Your not meant to wait till the ice melts, your customers are meant to drink it before the ice has melted... then bin it...
Cream is more filling than the normal drink. So this improves the drink from standard, making the drink more filling and lowering the need for another drink...
Ice is one of the oldest cons in the fast food drinks...