The issue with focusing on realistic estimates is it omits the psychology of deadlines, incentives, ownership, competitiveness and determination.

Going back to your university days, who hasn't left things to the last minute and been amazingly productive in the last couple days before the coursework or exam was due?

The issue with aggressive deadlines is burnout, creative oppression, flawed risk management etc

As always it's a balance. Grass is always greener but chances are it's neither.