@
yaffle,
A bit of background: XBMC/Kodi is a media player. That is a piece of software that takes a media file as input and plays it back. Granted, in practice is does much more, as it organizes your media, and presents is a clean and clear way, plus much, much, much more.
Plex, Media Browser, and a few others are Media Streaming Servers. They take a media file as input, transcode it, then stream it to remote devices (TV, HTPC, Smartphones, Tablet,etc). Because they transcode the source, they can adjust the bitrate of the stream to accomodate they remote device and the network bandwith, so that in theory, the media plays smoothly regardless of the device used to view it. So with a streaming server, you can access your media anywhere, on any device.
XBMC will play media whose codec is supported, as-is. And although possible, playing a remote source on XBMC is rather difficult and the results will vary. For best results, XBMC is best deployed on a gigabit LAN...
Having a centralized server, allows you to update your library without the need of having a client running at all times. It also allows you enjoy your library anywhere you are. It is like having your very own netflix, spottify and youtube.
Plex is the most popular of these, but it is closed sourced. Media browser 3 is open, but lacks the maturity of XBMC. By merging XBMC and MB3 you get all the new functionality of a streaming server, coupled with XBMC client functionality...
My fear is that as plex and mb3 become more popular and feature rich, new users will flock to these solutions and will never try other alternatives, namely XBMC/Kodi. This would be bad as it would further marginalize XBMC/Kodi