I'm not saying people don't do it now in the real world or even the SR world, I'm saying it's less likely in the Shadowrun World.
Yes you can get Open Source or Pirated Software but then we're talking Program Degradation as per the rules on Open Source (Unwired p 110) and Pirated Software (Unwired p108), and other negatives such as lack, restriction, and/or limit to options and ratings. Keeping software patched up can be an expensive and/or time consuming proposition. It can easily eat up a huge percent of a Hacker character's downtime, time that could otherwise be invested in skill development, etc.
Also, hosting Open Source programs that are illegal (most hacking programs) can be a problem. In our world it's not that big a deal if the country of the host has lax laws, but in SR G-O-D has jurisdiction just about everywhere (all places that recognize the Corporate Court if I recall correctly... that's a LOT of places). There will be those who like to snub their noses at them of course, but they better stay under the radar if they know what's good for them.
A personalized program/agent/etc with few existing copies shouldn't (though some GMs may disagree) degrade too quickly or at all given that security measures are only encountering it rarely, thus fewer updates to counter their effectiveness (speaking about hacking programs mostly), so patching to stay current would be far less necessary.
Just my two nuyen.