I would like to remind you what has been introduced in patch 4.0 because you complain a lot, and the game looks much better than version 3.0. I will mention only what happened in the gamplay and editor, it's hard to call it a game break. The only thing is the infantry is leaving the place too easily under fire which seems safe.
In some cases, this is annoying just like spotting a short distance. However, you can still play it.
Vehicles have access to a new movement command called Hulldown. This command allows a vehicle to move forward until only the turret is exposed to a specified target, and then the vehicle stops moving.
Improved Infantry Spacing
Infantry on the move will now respect each other's personal space! While moving, squad and team members will maintain a few meters of distance between each other. Soldiers will also spread out laterally on the move when possible (some terrain may necessitate column movement, such as paths through rough terrain).
Peeking Around Building Corners
Infantry units positioned adjacent to building corners will now automatically post some soldiers at the corners to observe and fire around the obstacle
AI Proactively Avoids Artillery Fire
The TacAI that runs soldiers and vehicles will more proactively, and reactively, attempt to avoid incoming HE fire. Two classic examples are that the AI will attempt to avoid being wiped out by incoming artillery barrages and direct tank fire.
Combine Squad Command
Combine Squad is a new Admin Command for squads. This command is useful for squads that have suffered major losses and need to consolidate their remaining personnel into larger teams.
AI Area Fire Orders
The AI can now be scripted to use Area Fire! Each AI Order can have a target zone designated.
AI Facing Orders
Each AI Order can be given a location for it to Face towards.
AI Withdraw Orders
AI Groups can be ordered to Withdraw towards their movement destination. Vehicles will move in Reverse to the destination, while infantry will leapfrog back while turning around to face behind them.
Personnel replacements and ammunition levels are now more uniformly resupplied across all core units between campaign missions, as opposed to the all-or-nothing check on each unit done previously.
3D Flavor Object Clone Tool
Flavor objects can be cloned within the 3D view without having to go back to the 2D view.
32 Order AI Plans
Each AI Group can now have up to 32 orders, increased from 16.
Small streams can now be placed on battle maps.