Regarding your base question, foobar2000 is simply an extremely powerful, sufficiently minimalistic, extremely easy to use and extremely configurable music player with a clean interface and support for every format I can think of, including esoteric Amiga tracker stuff. In it I can also organize and control music by superior means to any other program I know of, by the virtue of its easily macro-able tagging and renaming functions. In pure functionality and usability in a single-computer environment, MPD, or any other music player I've ever seen, simply does not even begin to compare against it.
However, MPD has good qualities foobar does not have, the biggest of which being the ability for anyone in the household to connect to the server by terminal using any device. This is why I use it over its alternatives in Linux and prefer textmode clients, mainly ncmpc. ncmpcpp is also nice, but there are subtle differences in their operation principles of these two, that make me want to stay in the C version (#1 being the ability to remap keys easily). It would well be sufficient for general music usage, if it were not for several features it lacks.
1) Optional display of metadata from a selected / playing file on the fly, possibly in the lower part of the window. This exists, but in a different screen. Wanting to see the year a tune was made is pretty common.
2) Queuing of individual songs is impossible (this would be important because then people wouldn't destroy the general playlist all the time)
Especially the queue is something I understand people will ditch MPD over. More importantly, when I visited IRC channels frequented by client developers to ask about the issue, the main reason people claimed the clients they wrote did not support this feature was, that they were waiting for MPD itself to implement it in a non-hack way, so that their clients would not break in the future for trying to implement it themselves. I.e. the lack of the feature is also a (at least superficially) legitimate reason to ditch MPD, not just one of its clients.