People like things to be consistent and reliable. When we’re talking about technology, they probably don’t know what specific coding or licensing or development practices lead to that, but they know that they don’t like it when something they use gets worse over time.
When things they use everyday change at the whim of one company that has full control, they don’t always like it. Having software that’s free to modify and distribute makes it so people will always have options and not depend on one company or another having the same opinions about what makes software good.