The data lake introduces a new data analysis paradigm shift:
OLD WAY: Structure -> Ingest -> Analyze
NEW WAY: Ingest -> Analyze -> Structure
This allows you to avoid a lot of up-front work before you are able to analyze data. With the old way, you have to know the questions to ask. The new way supports situations when you don’t know the questions to ask.
This solves the two biggest reasons why many EDW projects fail:
Too much time spent modeling when you don’t know all of the questions your data needs to answer
Wasted time spent on ETL where the net effect is a star schema that doesn’t actually show value
There are some good details here. My addition would be to reiterate the importance of a good data governance policy.