Apart from Pertwee I thought they were the best two versions.... but you must remember when they took on the role "60" was deemed ancient, whereas today - despite the annoying obsession with youth - you see 70 year olds in track suits etc and don't really consider them "old"
Capn' W's point about "why should it matter?" is a pertinent one - it shouldn't, so why be coy about it?
I think wec has put his finger on it: the public are just plain nosy and like to know these things. Notice on the news whenever a celebrity passes on, one of the first things they announce is their age. Those who try to fudge, mask or hide it merely fuel the intrigue...
There was a brief but interesting debate about ageism recently on Newsnight. Sadly whereas advanced years were once respected as an accumulation of experience and wisdom, in today's stress-propelled 100mph instant-fix society if anyone can be bothered to pause and even acknowledge the elderly it's more often than not to patronise them. Which is a bit odd when you remember we're mostly living longer and the population's getting older.