Like the people who work on movies and TV shows, developers want to be acknowledged: in many cases, being able to prove you were associated with a project is an end in and of itself.
This is especially true in game development, even AAA titles made by massive game development shops: they even roll credits just like they do in the movies. The International Game Develpers Association (IGDA), is the game industry's version of the Screen Actor's Guild and and provides a set of standards that games need to take to credit everyone who works on it: from developers, producers, artists and even testers.
Even in major pieces of software, the practice of crediting the developers who worked on a project still occurs:
If you're curious as to why you see their names on a splash screen when loading the program instead of hidden somewhere else, especially in large, monolithic programs like Photoshop or Office: well, it has very little to do with acknowledging people: it's to give people something to look at while the program loads itself into memory.
But this isn't just for offline software and games written by large corporations: knowing who made a piece of software is important for online startups, too:
And for Open Source projects:
In fact, listing who is associated with a project helps to attract more talent, in much the same way advertising who's attached to a movie helps attract movie stars.