I actually think we should have max voting ages - it should probably be tied to when retirement benefits kick in (ex. 65).
After that, you may advocate politically, you may still run for office - but your time as a voter has ended - you had your time to shape the country, now it's time to pass the torch.
Initially I was also hesitant about this stance given the rapidly growing lifespans we have seen over the past century, and will see over the next century. Instead, my position there too has changed - because old people generally accumulate more clout and power as they get older naturally - they don't generally need their vote to make an impact. A 200 year old dude has been shaping the world around him for centuries - he doesn't need to show up in the polls to have an impact.
Particularly if he's managed to grow his wealth and power during that time - he has a massive advantage over the young 65 year olds just starting their potentially long lives.