The thing is, senior programmers really aren't always that useful. We want leadership, we want big meaty projects and problems, we know so much and can do so much... Except that sometimes what needs doing is boring. It's grunt work. It's some infrastructure migration or a real simple API addition. A lot of coding is actually not that hard depending on where you are. That work we consider grunt work is a great way for a junior engineer to learn and they don't complain as much as we would. I've worked with a lot of other senior folks and (like myself) and we have entire abandoned features because no one wants to own them. It's a gift when someone junior shows up and jumps in.