Less than 10% of all developers will do the latter option. Remember - this program was working long before you go there. It makes lots of money. Therefore, it's got to be doing something right.

So I take it that option 3 is what you are advocating as a reasonable approach, while option 1 and 2 are less reasonable. I think that all of those options have upsides and downsides:

• Option 1 upside: Get paid while it works.
  Downside: uncaught system bugs get you fired, perhaps.
• Option 2 upside: Low stress at work.
  Downside: No job.
• Option 3 upside: Get paid while it works.
  Downside: uncaught system bugs get you fired, perhaps.

So I don't see a lot of difference in 1 and 3 until after your discussion with the boss. Even then the defacto corporate programming methods/policy isn't likely to be changed by your middle manager. After all you said it has been working the old way making $$$ so why change?

OTOH, making changes to the Modules you modify, and applying more sane programming practices yourself, quietly, over time, would seem to be an option 4 which would be compatible with option 3 and perhaps more likely to change the defacto corporate programming practices? No?