Why Do We Need an Acronym of the 10 Plagues? Why Do We Take Out Some Wine?

After enumerating the 10 Plagues in the Hagada, Rabbi Yehuda adds an acronym, enumerating the Makot by their Hebrew initials: D’TZACH ADASH B’ACHAV. Why was this necessary? We already have recited all the Plagues! One answer is that it helps the children learning about the Exodus remember the Makot (& children are the essential audience at the Seder). It also indicates two patterns: 1) Before the first 2 Plagues of each group, Moshe warned Paro of what was coming. But the last Plague of the three came without warning. 2) The first 3 Plagues were brought by Ahron, using his staff. The 2nd group was brought by Moshe without the use of his staff, while the 3rd group was brought by Moshe with his staff. As for removing a bit of wine, there are 2 opinions: some say it is to lesson our joy ("wine makes the heart happy") because so many of G-d’s creations died at the Yam Suf; others say it represents the enormous amount of Jewish blood that was spilled in the course of 100+ years of cruel slavery.