Not reading the documentation (or hell, the red "note" text under each 32 bit download link at http://www.mongodb.org/downloads) for basic limitations will bite you in the ass in 2022 just as easily as it will in 2012.
I'm hardly an inexperienced programmer. I've used Cassandra, SimpleDB, Voldemort, etc. I wrote part of the Inktomi Search Engine in the 90s, and plenty of (what today would be called) NoSQL stores over the years.
A default that's so counterintuitive for a database should be featured prominently with a huge neon sign. It wasn't in the Ruby tutorial, or in any of the many documents I read. It's buried deep in the Mongo website, and the first Google match about the 32-bit limitation is a blog post from 2009.
Sometimes you just have to admit you screwed up and didn't read the documentation. Everyone does it, we're hackers, we'd much rather play with technology than read docs.
That 2009 post is the canonical post about the issue, which is why it has such page rank. Its position is a consequence of the fact that it's linked to from all over the web, not because nobody has discussed it since.