We've just released a patch to re-enable harvester crushing, something many of you remember from our launch and have asked for. Harvester crushing now works in the following way...
Multiplayer Quickmatch / Ranked games preserve the no-crushing rule for Guardian and Renegades Harvesters
Skirmish and Custom Multiplayer Games now provide a checkbox option for turning harvester crushing on/off.
Single & Multiplayer Co-Op campaigns have Harvester Crushing Turned on by default.