I'm in the midst of maintaining/fixing one of those and I find it a great opportunity if you A) want to learn outside your comfort zone, B) enjoy figuring out problems that aren't just technical (talking to people, design, organization), C) want to get out of a coding-grind lifestyle.

Our organizational structure isn't immutable, it just moves slowly. After about a year, my team's effort resulted in measurable improvements for both revenue and end-user experience.

If you're senior dev level and want more of a challenge that's not just throwing more code at the wall, these sorts of scenarios are something to seek out.