Is there an Arduino (software) team?
Here is some proof of their absence. Statistics show significant drop in activity over the latest two years.
https://groups.google.com/a/arduino.cc/forum/#!forum/developers
The major contributor(s) to the software part of Arduino have "left the building". There is no "software architect" as no money is made on software licensing, etc. This is good and bad. Some of the contributers the latest years are people giving back as they are trying to start businesses based on Arduino clones and rely on the software.
Arduino(TM) is about branding and marketing -- BOARDS. There is a lack of investment in software. This is the Achelles heel of this business enterprise as it should/must include software and software quality. Checkout the endless discussions on "clones" and "counterfeit". How often does the "Arduino Team" present something regarding improvements in software architecture?
My guess is that the Ethernet library is not maintained by the original author (any more) and it is only contributions from users that "develop" it further. The actual implementation is also on top of another library which is actually written by one of the more important maintainers and developers right now. If you check the source code you will see there is actually no author reference to Ethernet.h and Ethernet.cpp. The Dhcp class has the following info:
// DHCP Library v0.3 - April 25, 2009
// Author: Jordan Terrell - blog.jordanterrell.com
If you check "blame" in git you can actually see the changes to the Ethernet library over the years.
Cheers!