I'd have to agree with being skeptical about new revolutionary ideas. Besides being rehashed old ideas, or just passing fads that won't necessarily catch on, from what I've seen over the years a number of those revolutionary ideas are either solutions looking for problems, or solutions to actual problems that actually create bigger problems somewhere else.

In this case it looks like people from the "relational databases are bad and slow" camp had these built, becuase they didn't understand or want to deal with technologies like replication, or understand how to properly tune a database application to use the system resources most effectively.

I suppose these technologies have their place, but the danger is that too many people will build applications that depend too much on the non-relational system as opposed to just supplementing the RDBMS, that's when they will create other problems.