Could be that wireless tech exists, but is traceable and sets off intrusion alarms and such. Like the tech in Star Wars is advanced to the degree of making wireless access obsolete for any practical, story-impacting purposes. "It's just not worth the risk," unless there is no other option.
An alternative (and also totally realistic answer) is frequency. This is actually becoming a real world problem. There's so much wireless tech out there that it's all rapidly encroaching on itself, essentially it's all these devices are unintentionally jamming each other. In Star Wars there might just not be enough physical bandwidth for any "nonessential" wireless communications, with the ICC stomping down on anything beyond licensed comlinks and the like.
Though since with Star Wars we are also talking military, or military-grade systems it might just be a simple issue of the military not putting anything that sensitive on a wireless system at all. My RL employer is actually on the forefront of military commo and networking, and a huge part of what's going on is just keeping everything from jamming each other, keeping everything running when jamming is going on, and keeping the unclassified, the sensitive, and the secret from ever touching.
Third, I'm not sure sputnik is a good example of Star Wars technology, since it was launched in 1957 and was incredibly unsophisticated even by 1970's standards. It also communicated via radio waves, not in a near-instantaneous faster-than-light manner in which these Star Wars devices operate. It also only really had two functions: transmitting radio data and monitoring temperature.
Three functions. Radio beacon, temperature, and doing it first.