1 — The “10 Plagues” demonstrated G-d’s superiority over human power.
While Pharaoh commanded Egyptian military personnel and technology, G-d commands nature itself. The 10 demonstrations were not “natural” phenomena, or they would have affected the Israelites along with the Egyptians: “I will set apart in that day the land of Goshen, in which My people dwell, that no swarms of flies will be there; to the end that you will know that I am the L-rd in the midst of the earth” ; “…the L-rd shall make a division between the cattle of Israel and the cattle of Egypt…” ; “Only in the land of Goshen, where the children of Israel were, there was no hail” ; “…and there was a thick darkness in all the land of Egypt [for] three days…but all the children of Israel had light in their dwellings” ; “…but against the children of Israel, no dog will wet his tongue against man or beast [i.e. because none will die], that you may know how the L-rd puts a difference between Egypt and Israel.”  As Rashi says, “Although My Glory is [seen] in Heaven, My Will is omnipotent on earth.” 
2 — The 10 plagues served a dual purpose: They both humbled Pharaoh (or were intended to do so) and, at the same time, displayed to the Israelites, who were still enslaved, the power of G-d, in which they could have total confidence. In fact, there is one point at which the Israelites do: “And Aharon…did the signs [G-d had given to Mosheh] in the sight to the people. And the people believed…”  The subsequent fears, grumblings and defiance of the Israelites must then be seen in the context of the trust they were given the opportunity to have by the displays of Divine power even over “nature.”
We could incorporate discussion of the above at our seders, especially in the “Magid” section.
3 — We could — perhaps should — also include:
,באותה שעה בקשו מלאכי השרת לומר שירה לפני הקדוש ברוך הוא
:אמר להן הקדוש ברוך הוא
מעשה ידי טובעין
?בים ואתם אומרים שירה לפני
“…The Blessed Holy One does not rejoice in the downfall of the wicked. For R. Samuel b. Nahman said in R. Jonathan’s name: ‘…In that hour [the drowning of the Egyptians], the ministering angels wished to utter the song [of praise] before the Blessed Holy One, but He rebuked them, saying: My handiwork [the Egyptians] is drowning in the sea; would you utter song before me?'” 
“Why does Scripture give no [explicit] command to rejoice during Pesach?
Because the Egyptians died during Pesach. And similarly do you find that although we read the [entire] Hallel on each of the seven days of Sukkot, on Pesach we read the entire Hallel only on the first day and on the night preceding it. Why? Because of what Shemuel would quote: “Bi-nefol oivekha al tismach” – ‘Don’t gloat at the fall of your enemy.’ .” 
Twice this season I heard Jews — unknown to each other — express discomfort at the death of the first-born. The above could be applied to that part of the discussion, too.
 Sh’mot/Ex. 8:18 If it were a purely natural phenomena, Goshen would be infested as well. Here, G-d’s statement not only demonstrates Divine Power over nature, but Divine Prescience as well.
 ibid 9:4 [And the L-rd did that thing on the next day. All of the cattle of Egypt died, but not one of the cattle of the Israelites died (9:6)]
 ibid. 9:26
 ibid. 10:22-23
 ibid. 11:7
 quoted in Hertz chumash, p. 240
 ibid. 4:30-31 [only to reject Mosheh shortly afterward (6:9)]
 Megillah 10b and Sandhedrin 39b
 Proverbs 24:17
 Pesikta d’Rav Kahana 189a, quoted on: