Thanks for sharing your story!

Yeah, I also initially felt this is some kind of failing (I'm usually the "big picture guy"), but ended up accepting this as a coping mechanism. It's not that I forget about the purpose completely - just learned to think about it more when planning and designing, where the wider perspective also affects the task in a meaningful way. When deep in the codebase, I try to put it aside, so that I don't get in a depressive session of thinking "why do I have to shovel this garbage back and forth to satisfy some low-level requirement, instead of, I don't know, talking to people who'll use this on-site and getting some real feedback from them?". Rationally, I know that shoving garbage is an important part of getting quality software that helps others do exciting things. Emotionally, I just wish I was in their shoes (probably just as much as they wish they were in mine).

You seem a bit more positive than me when facing this reality, so I'm glad you have it in you to enjoy this. I almost have it, so I find ways to cope, and enjoy the opportunities to do something less mundane that come every now and then in such projects.