It sounds like it's about the jet's own survivability. But even then adding drop tanks and conformal tanks can boost the range. A lot of foreign F-16 customers are using those because they don't necessarily have any other long range options.
Couple of things to consider. One is that all fighters that operate in a hostile environment against opposing forces that aren't stuck in the middle ages need self protection electronic countermeasures. The second is the F-16 is capable of and is used for long range operations, especially when combined with in-flight refueling.
The F-16 was slated to get an internal jammer called the Advanced Self Protection Jammer (ASPJ). As the timeline for that program kept slipping, the internal space reserved for it kept decreasing, the threats kept advancing and the cost kept skyrocketing, the AF canceled the program and continued to hang ECM pods on the Vipers.