Some people don't always like to jump from project to project. Sometimes I don't either. I guess you get tired of switching context; of having to learn everything again without the satisfaction of resting on past accomplishments.
Focusing on one project, or one type of project, or one vertical, or anything predictable and constant offers the opportunity of specialization, and that's a great thing. You definitively don't need to jump like crazy, but you also get the benefit of becoming excellent at it.
That's a great thing, for sure.
But the same could also become annoying. Even worse, it could lead to stagnation which could quickly destroy a good team really quick.
Going from "cutting edge, awesome team" to "old, stuck in the past" doesn't take that long in the software world. Things change too fast for us to get too stuck in old ways, so anything that offers an outlet to try, improve, test, fail, start again is a blessing.
Remember this: your sharpest engineers will never put up with the same project for too long. They understand they need to move on, to learn new things, to improve.