In the OP video, Sussman mentions that SICP was one (the first) of four core courses in EECS that introduced essential concepts in programming, circuits, signals and systems, and computer architecture. I think all four completed by the end of year two and were prerequisite for all junior/senior EECS courses thereafter.

It's hard to imagine the EECS program does not still require this material to earn a BS in CS or EE, but requiring four prerequisite courses probably interfered with non-EECS students who wanted to take junior/senior level EECS courses but did not want to have to run the "gauntlet of four" before doing so.