Meaningful dick jokes explain this film's popularity.
Trainwreck is a delightful modern take on an oft-used storyform. Main Character Amy (Amy Schumer) is the single lady saddled with the daddy-inspired emotional baggage of putting off long term commitments (Main Character Domain: Situation, Main Character Concern: The Future, Main Character Issue: Delay). Romantic interest and Influence Character Aaron (Bill Hader) provides the emotional challenge needed to force her away from the negative behavior of avoiding relationships (Main Character Problem: Avoidance) with his positive outlook on her actions (Influence Character Issue: Hope). Amy's sexy dance performance offers proof of this paradigm shift (Main Character Resolve: Changed) by showing her actively chasing after Aaron's affection (Main Character Solution: Pursuit).
A common shift for Main Characters--that of moving from Avoidance to Pursuit--yet one that elevates this film beyond a meaningless mish-mash of dick jokes and jocularity. The integrity of the storyform underneath it all explains the score of 85% on Rotten Tomatoes and offers an example for other comedies to follow.