Here is a selfish reason for you to support/encourage open source....Just image the company/programmer/source of the program/code/etc that you love/use daily has disappeared from the face of this earth for some reason(eg. company bankrupt, programmer(the team) with the knowledge was disbanded/let-go, source code destroy by fire and etc) and you have just discovered a specific bug(that is critical to your need). What would/could you do now? So, here is what open source can do for you:

1. If you got the source code and you have the skill set and the time, you would fix the code yourself
2. If you got the source code, you can hire someone with sufficient skill to fix bug or add stuff for you.

A side benefit: you are not lock-in to the company that provides you the original program to begin with. You would choose to stay with the company, if they provide you with acceptable(ie. to your standard, eg. how long is too long to be waiting on the phone for the support call) of after sale-service(eg. bug fix, responses to enhancement requests)

Open source s/w development turns the s/w company business model from that of selling widget to that of services. Many traditional s/w companies do not like it; because they can no longer use the lock-in to make their money.

I will let other to discuss other non-selfish good social benefits of the Open Source development model and GPL.

Cheers,