The price I pay for this is earning about 10k€ less a year, but I still think it's worth it.
If you're a creative developer, or you have a passion for a specific area, then it's easy to ignore "unassigned work" in favour of doing things that you want to do instead. There can be a great deal of value in that that any manager needs to recognise. Someone who isn't voluntarily picking up unassigned work isn't (necessarily) failing to show leadership - they might be leading in an area where work isn't being created, whether it's assigned or not.
http://www.moneychimp.com/calculator/compound_interest_calcu...
values of 0; 10,000; 20; 4; results in nearly 310k of missed gains.
Increasing that 4% to 8% increases it to nearly a half a million!
At my estimated retirement income requirements, that basically means I could quit working 10 years earlier if I don't settle for being underpaid.