Why did Jesus use the word "dry" there? The simple answer is that I don't know. However, I'll guess.
We may see here the idea that a person who does not have God's presence is like one in a dry area. It should be remembered, though, that the text also has a heading for this Psalm: "A Psalm by David, when he was in the desert of Judah." David may have literally been in the desert when he wrote this.
There's Psalm 68:6 God sets the lonely in families.
Isaiah 44:3 says: For I will pour water on him who is thirsty,
Ezekiel 30:12 and Hosea 2:3 speak about God abandoning Israel to the desert.
The Greek word translated as "wilderness" in some versions of Matthew 4 (and Mark 1 and Luke 4) is also translated as "desert" in other places. Probably Jesus met Satan in a dry place. The Blueletter Bible gives all of these occurrences, here.
So there are positive associations, related to God's presence, with being watered, in the Bible. And there are negative associations connected with being in a dry land. Probably that's why Jesus used the words He did in this case. But that's just a maybe.
Thanks for reading!