Being able to GTFO is easily the most undervalued skillset in TTRPGs. To use 5e as a common example, stuff like Spike Growth or Fog Cloud are essential TPK prevention solely for covering a hasty escape.
Still, it's easy to understand why retreat is so undervalued. Lots of systems actively aim for really swingy combat, where one side or another ends up dead before retreat can really even be considered.
One of the reasons I'm not fond of "snappy" 2-4 turn combats.