Why isn't the Rapid Fire Autocannons optional rule in Battlemech Manual?

[FixDis]

I know it's controversial as a rule, but why is it relegated to Advanced Rules and Equipment?

[Xotl]

There isn't any special reason, other than I didn't have the sense that it was a popular rule at the time.  Were I to do the book again I'd probably add it in some form, but it was really quite arbitrary as to which ones made it in.