This is a legitimate question because, as opposed to other professions such as the ones you mentioned, software engineers very often do not change the world at

This is a legitimate question because, as opposed to other professions such as the ones you mentioned, software engineers very often do not change the world at all. A lot of software projects fail, have a very short lifetime, replicate something that already exist or do something that may not seem very useful (eg. the plethora of "social" apps). In all these cases, the impact of software engineering is actually rather negative: wasted natural resources, wasted time, etc. Even when the software is innovative and has users, we can often question its usefulness for humanity. For example, high-frequency trading or mass destruction weaponry are fields where the question of meaning may arise. I think the question of meaning is important to software engineers because it's not obvious at all that what they do is meaningful.