Because looking back at the decades of your work while being retired is just a sweet ethical exercise with very few direct personal and financial consequences.
If you are an engineer employing dark UX patterns _today_ you must look at yourself and evaluate the ethics of your work _today_. This will likely have direct personal and financial consequences.
If you are an engineer employing dark UX patterns _today_ you must look at yourself and evaluate the ethics of your work _today_. This will likely have direct personal and financial consequences.
So the stakes are completely different.