The Alshich writes that by stressing that Haman hates all the Yehudim, Mordechai was making it amply clear that Haman’s hate was not just a personal vendetta against him. Indeed, as noted earlier, he hated all Jews.
In that sense, according to the Me’am Loez, Haman was worse than Pharaoh; whereas Haman (Esther 3:13) wanted to kill all of the Jews, Pharaoh (Shemos 1:16) wanted to kill male Jews only.
R’ Meir Simcha of Dvinsk notes that, historically, hatred of Jews escalates when they ignore their faith.
As the Rosh Yeshivah of Brisk, R’ Meshulam Dovid Soloveitchik, explains, Haman hated all Jews, regardless of the efforts of some to conform to his whims in an effort to befriend him, like those Jews who attended Achashverosh’s feast against the advice of their contemporary sages.