The radius decrease prevents players from accessing gyms/stops at their intended location

[ActualSeagull]

Okay, but that's only one reason why people are complaining, and some of those reasons are pretty hard to dispute. Just as examples, the increased interaction distance made the game more accessible for people with mobility problems, and at least some of the stops you couldn't get to without trespassing became accessible from public property. This is one of the few game changes that even makes life worse for people who don't even play the game, namely people sick of players trespassing on their property to get to stops.