Why does the Torah mention Yetzi'as Mitzrayim here?
Rashi: To teach us that keeping the Mitzvos was a precondition of Hashem taking us out of Egypt.
Seforno: Because Hashem took us out of Egypt in order to sanctify ourselves and to thereby earn His Goodwill - that He would be our G-d without an intermediary, and that we would be holy and eternal by imitating Him in personality-traits and in knowledge - since He is Holy.
Why does it use the term "ha'Ma'aleh Eschem"?
Rashi: It implies that if Hashem had taken us out of Egypt just so that we should not contaminate ourselves by eating vermin like the other nations it would have sufficed - because it raises us to a higher Ma'aleh (level).