A couple of times I have wondered why people use SQLite - why use a library and a file when you can easily have a real [RDBMS]?
Perhaps the attraction is the very low barrier of entry to creation, administration and connecting - when you Just-Want-To-Start(tm)¹, these chores of setup are tedious and in the way.
Does that mean that SQLite is the Access of Free Software? ;-)
Maybe SQLite could also prove to be practical when writing tests for modules that depend on database-access? Hm.
¹ And that is usually what you do, when you get an idea and lunge forward in fleshing it out, right? :-)