There's probably a modest financial incentive in interactive agencies to avoid dynamically updating dates so a client comes to you at least once a year for some

There's probably a modest financial incentive in interactive agencies to avoid dynamically updating dates so a client comes to you at least once a year for some cleanup work where you can try and sell them on new work. But from a legal perspective (IANAL) my understanding is that dynamically updating copyright dates in and of itself is probably never a legal problem, but the issue is dates in other legal boilerplate (random disclaimers under a financial services company or health disclaimers on a pharmaceuticals ad, for example). I think the lawyers' thought process about never wanting dynamically updated dates anywhere is that if the web workers get in the habit of dynamically updating copyright dates, they're going to apply the same logic to any of the other legal disclaimers on a corporate site, which could turn out badly. There might be a financial regulation active in one year that's not required in the next. There might a change in FDA regulations and updating the year with the old regs still on the site might be seen as a false health claim, etc. A dynamically updated date in a legal disclaimer can be a major problem. The safest thing to do to avoid a big screwup is to tell the developers "no dynamically updated dates" ever.