Default Data Wire Thickness in the Editor Preferences only affects Single Value data wires. Containers (Array, Set, Map) line thickness are wrongly tied to Default Execution Wire Thickness.

Changing the "Editor Preferences > Content Editors > Graph Editors > Tracing > Default Data Wire Thickness" value in the "Editor Preferences" only affects single value data wires. Containers (Array, Set, Map) data wires line thickness are tied to "Editor Preferences > Content Editors > Graph Editors > Tracing > Default Execution Wire Thickness".

1. Create a BP
2. Create 4 float variables and name them FloatSingle, FloatArray, FloatSet, FloatMap
3. Change the second variable to Array (select it and change in the Details pannel), the third to Set, the fourth to Map
4. Pull all variables to the Event Graph and choose Set...
5. For each variable, pull a data wire from the Left side and Make... the corresponding data type (Make Literal Float, Make Array, etc.)
6. Change the values in the "Editor Preferences > Content Editors > Graph Editors > Tracing > Default Data Wire Thickness" and check that the only line affected was the one connected between MakeLiteralFloat and FloatSingle
7. Change the values in the "Editor Preferences > Content Editors > Graph Editors > Tracing > Default Execution Wire Thickness" and check that the data wires for FloatArray, FloatSet, FloatMap, were all affected.