In colloquial english we usually put an "or" in front of else. It really breaks down when you put it in boolean form because the "or" implies other actions when true rather than actions if false. Removing the "or" completely is unambiguous but is antiquated English.

Examples: "Go to college or else work for your uncle"

Turn this into boolean form: "If you go to college then <foo> or else you will work for your uncle"

But the "or" makes the meaning ambiguous: "If it rains then I will work inside or else I will work outside."

It is not clear if this means you will work outside if and only if it is not raining? Maybe working outside is another option if it rains.

Otherwise is far more clear. "If it rains then I will work inside otherwise I will work outside."

Removing the "or" completely makes the statements unambiguous archaic English: "If you go to college then <foo> else you will work for your uncle" "If it rains then I will work inside else I will work outside."

FWIW - I am very glad they chose else over otherwise...