To extrapolate this incident to "companies will start snatching up three letter names, and nothing will ever be able to use a three letter name" is ridiculous.
Kik is a messaging app, kik is a node module. Was someone going to call up the app store and install a node module? Was someone potentially going to install a messaging app into their node project?
I think there are a lot of slippery slopes here.
Who actually installs a module without actually seeing what it does first?
Field however is hard to define, for example Trademark offices have categories and theoretically, you cannot have 2 trademarks owned by 2 different entities. That said, it does happen, because the "fields" are actually defined by likelihood of confusion, which is shown in court. If this is all confusing, it is.
But long story short, if your mark is famous (and kik's would be considered famous), you're the only one allowed to use it, and you HAVE TO in force it, otherwise, you lose it.