I think they changed it more so that Sivir: [A. didn't have autocrazyfarm and B. absurd teamfight damage] so that she could be good but not broken. The thing about old Sivir was that her bad passive and poor range made her abilities bad, but they probably found that Ricochet with the range increase became ridiculous. I mean there's other reasons related to what you said but you are reading way too deeply into things imo.
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Boomshine
~Justin_Crossing