Bloomberg's main product offering is still the data feed though. The "application" part of it definitely makes it easier to use but a lot of trading desks build their own algorithms and pricers on top of that data for the functionality they really need. The built in stuff bloomberg has tends to be overly simplified
This has not been my experience. My view of Bloomberg is two primary products: (1) Bloomberg terminal and (2) Bloomberg BPIPE.
(1) is a desktop (and now mobile) application that trader, sales, etc. use to communicate, view raw data, and view derived data in "mini-apps" (price this bond under scenario X, etc.) The base cost is about 25K USD per year (there are local IT costs above the terminal license fees). There is a raw data access API for Excel, but very limited. They block your API access if you try to download too much data. The days of pricing any kind of volume of products from a Excel Bloomberg API is mostly gone. Also, you cannot run it on a server and just screen scrape / use data API all day long.
(2) is a raw data feed service, akin to Reuters. Not well understood by industry outsiders: There is no "all you can eat data service" anywhere in finance. Period. Every primary data source is now carefully guarded with license costs and special rules (no redist, etc.). Some stock exchanges make more money selling data licenses than collection trading fees! I have no idea about BPIPE prices, but I assume expensive and per data source with nearly infinite granularity.
If you believe it: 20K USD per terminal and ~325,000 terminals as of 2016. That is 6.5 billion USD per year. Nice.
About revenue: (2) No idea. I cannot find any reliable published stats.
Lastly: I regularly see people argue on HN about an open source version of Bloomberg. It is impossible for two reasons: (a) Network effect in the communication channels -- lots of people mostly use Bloomberg chat / email and hardly use data, besides the trivial. Most people on the buy side (money management, hedge funds, portfolio managers) join Bloomberg to talk to other people on Bloomberg. And: (b) data licensing.
