Just so I’m not making blanket statements without providing any examples, off the top of my head here are a few great ensemble-created shows from the past few years:
The Sound and the Fury (NYTW) and Gatz (Public) by Elevator Repair Service
Architecting and Particularly in the Heartland (both PS 122) by The Team
I’m Going to Make a Small Incision Behind Your Ear to Check and See If You’re Really Human (Bushwick Starr) by Witness Relocation
Paris Syndrome (HERE Arts Center) by ExP.Girl
Any of the Nature Theatre of Oklahoma shows, especially No Dice (Soho Rep) and Romeo and Juliet (The Kitchen)
Any of the Big Dance Theater shows, especially The Other Here (DTW)
Any of the Big Art Group shows, especially SOS (The Kitchen)
That being said, terrible ensemble created theatre is one of the worst circles of bad theatre hell. :)