@MojangMoesh
This should still be considered. The net code already has enough issues on it's own and this behavior just makes the life of anticheat developers much harder. And if bandwidth is a concern, a gamerule could be added for this, so every server could decide if this is the behavior that they want. (/gamerule sendIdlePacket, for example)
This issue (alongside the 0.03 position threshold) has actually caused vanilla gameplay bugs, see MC-224949
Re-adding the idle packet (and removing the position threshold) is needed to stop client-server position desyncs and the issues that are caused by it. The idle packets existed in 1.8 and they worked just fine.
And even if the issue didn't affect gameplay, there's no reason not to fix it. Both mod makers and players would benefit from it.
Additionally, if a modified client changed the code to remove idle packets, it's easily detectable.