1)
Why does it say "Al Ken Saru me'Acharav"?
1.
Rashi: Here, Al Ken means 'because', like "Al Ken Yadata Chanoseinu ba'Midbar." Because they veered from Him, and brought in front of Him screams of the poor.
2.
Malbim: Because He does not openly punish Resha'im, He left a Safek about Hashgachah. Therefore, people veered from Him.
2)
What do we learn from "v'Chol Derachav Lo Hiskilu"?
1.
Malbim: Man does evil, for he does not realize that Hashem hid punishment of Resha'im, to leave room for choice!
