"recommended" works both ways.
for admissions, a student that shows a high level of preparation (i.e. biochem) will definitely interest adcoms. that doesnt mean it's necessary. doing poorly in biochem would likely hurt an application. i've heard of students whose acceptance was dependant on getting an A or B in a "recommended" biochem course. Why? they had great dats, poor science grades. the adcom liked the student, and wanted to see how they perform in biochem.
as for the student, i would say it's incredibly important. at my school, it's generally the most difficult course of the first semester. the students that are having the most trouble are, surprise, the students that had no undergrad background in it. to quote a classmate, "i feel like theyre speaking japanese up there ."
take biochem. do well. you'll appreciate it in the end.
however, i will admit that biochem courses vary a great deal. my undergraduate course required a ton of memorization. and it was designed for biochemists, not dentists. tough call.