I think mongodb is following a similar path to what MySQL did. Be really good at one thing, market as something else -- and then slowly, slowly catch up to the hype (sort of).
As I understand it mongodb have changed the default settings (probably why someone downvoted you) -- but the fact that it was off by default is still something that is rightfully hard for the team to live down.
And while a lot of people are probably still happily using MySQL -- I personally see little use for it, when PostgreSQL is an option.
I maybe wrong, but I think both mongodb and mysql appeal to the same groups: people that don't know or care about normalization, databases and datastructures -- and really just want image (as in Smalltalk) based development, but has been tricked into using php/javascript etc.
It's kind of crazy that you have two mature (one Free, one free) object databases that have seen some real-world usage -- and neither get any love.
One is zodb, the Z object database, developed for zope/plone -- one of the first web application frameworks -- and a major contributor to python (invented eggs, buildout...). It's ridiculously easy to use outside of zope/plone/pyramid[1] and now has a free replication service[2].
The other one is gemstone glass[3] which works with Smalltalk and have their own ruby runtime, maglev[4].
[1] http://zodborg.readthedocs.org/en/latest/documentation/artic...
[2] http://www.zope.com/products/x1752814276/Zope-Replication-Se...
[3] http://seaside.gemtalksystems.com/
[4] http://maglev.github.io/
