It's actually a very complex statement it's neither nihilistic nor insane. As with all words and phrases in English language, It will mean different things to different people. If you see it as a stupid comment made by stupid or lazy people than that is just one perspective.

Regardless from where it was derived, it can simply convey a verbal shrug and submission to the way things are OR it can be a comment made to convey the terrain and which one finds himself. It doesn't necessarily mean the established obstacles are insurmountable or unchangeable but it's a good starting reference worth mentioning in a complicated situation. It makes one start at square one and allows them to take appropriate action to either navigate or overcome said obstacles.

This is obviously an implied use by someone who is either educated or experienced in some matter as opposed to someone else who may use the phrase if completely out of depth or breadth and therefore disinterested in a solution. In this way the subtlety of this phrase can be a useful tool, but it can also be abused and used as an excuse.

Yes, it is a worthwhile phrase. It is only stupid to those who are stupid.