Give them to work in what they want to work. Or not.
We still need to be active.
However, why shoudn't they receive for their taxes?
Have you forgotten about all the time and energy loss in paying taxes to the government? Sure, these taxes were also to improve our conditions and of our countries, but they were also for pension funds.
Your apreciation, in my ignorant opinion, is incomplete. Give pensionists occupation, Sane occupation, Free and Whilling occupations, acording their choices, abbilities and vocation...
And, meanwhile, why don't we give it to everyone, in every age? Inspite our survival necessities, why don´t we do what we were born to?
...
Just a thought...