(I ask this because, for me, I think the former is much more likely than the latter.)
However, there are a ton of bioinformatics libraries released every year, and almost none of them gain any traction. Nature publications are far more frequent than important new libraries, and you need more political clout to get the library popular than you need to get a Nature paper.
Really, you need to gauge usefulness and interest of your library before you devote a ton of time to it. It's a lot like a startup's product.
Is it more important to get the result, or to use other people's code? Reinventing the wheel is a minor sin compared to not getting results.
The key is to find a modular component that is difficult or novel, and at the same time broadly applicable and hopefully extensible.
You aren't building a system for other users, you aren't really doing anything other than one-off analysis to create charts, which will be explained in a paper.
Things have changed somewhat since the early 2000's, but the concept remains the same. Nowadays, for interesting or controversial results other scientists want to be able to verify your results. However, that is usually more related to your data and how you processed it, rather than your software algorithms (which should be explained in the paper, and can be recreated from that).
So do these systems need to have reams of documentation? Probably not. However, if you leave the system for two years and come back to work on it, or figure out how it used to work, then you best have enough commenting with a thorough readme about some of the decisions you made and why. It's more analogous to scripting rather than software engineering.