Why are column store databases the new thing now?
By and large, I think the increase in the popularity of data warehousing is prompting the move to Columnstore indexes.

Columnstore indexes are geared toward increasing query performance for workloads that involve large amounts of data, typically found in data warehouse fact tables.

Columnstore indexes store data by column rather than by row. By storing data in columns rather than rows, the database can more precisely access the data it needs to answer a query rather than scanning and discarding unwanted data in rows.  

For wide tables, such as those commonly found in data warehouses, Column Store Indexes come in handy as you essentially reduce the amount and size of data needed to be accessed for any given query.

Check out some of these links for more information and examples:

Understanding the SQL Server Columnstore Index

Column-oriented DBMS

Columnstore Indexes in SQL Server 2012