Age Difference

What do you think about large age gaps in couples? 
Maybe I'm being a jerk but anything more than 10-12 years freaks me out a little. 
And I kind of feel bad for their kids. 
Say the female is 25 and the man is 50. When their first kid at those ages is 20 and ready to move out, his/her dad will be 70! 
Or when that kid turns 25 or maybe not even until 30, they're ready to get married and have their first kid, the dad will be 80! I can't even imagine not having my dad alive when my kids grow up and get married. Unless he lives until he's 100, he'll never see his grandkids be out of their teens! 
And not to mention, me as a wife, losing my husband before I'm even 70... I couldn't imagine. 
I understand the whole love is love concept...but honestly if I met a nice man who was 20 or 25 years older than me, the thought of "wow, he's hot and nice, we should date!" would never even cross my mind. 
Like I said, maybe I'm being a jerk. But that's my opinion. 
I'm interested in hearing your opinions for or against large age gaps!