Why is there a custom to say Shir Hashirim at the Seder? Isn’t it more important to talk about yetsiyas Mitzrayim?
While the mitzva of the night is to speak about Yetzias Mitzrayim, ultimately this should bring us to an elevated state of spirituality. Increased Emunah – faith and awareness in Hashem, Ahavas Hashem – love of Hashem by recognizing His kindness to us. In earlier generations this offshoot of fulfilling the mitzvos of Leil Haseder may have been more natural as they were more in tune with spirituality in general. In our times we often need to stop and reflect on these ideas in order to reap the complete spiritual gains brought by mitzvos in general and this night in particular, which is one of the foundations of our faith.
See Sefer Alei Shur Vol. 2 pg. 390.