As an informal observation, one of the best parts about older professors was that they avoid the extreme nuance that some of the younger professors and TAs get into. Although that can be interesting also, I feel as if it sometimes misses the bigger picture.

Older lecturers have had a lifetime to think about their problem domain and are often able to convey things very clearly and un-confrontationally. They aim to challenge you rather than defeat you. They are also less concerned with proving themselves and thus are generally more willing to lecture about things that are more in line with their true beliefs and aren't just designed to make them look smart. It's hard to put into words I suppose what makes talks like these so great.

On another note: this was basically a philosophy lecture which I think is great.