One reason that many Cocoon users have stayed with the 2.1x stream is that some very useful blocks never made the transition to 2.2
Personally, the hassle of migrating to 2.2 was not worth the gains it offered (Spring meh).
As we are all aware Web application development has evolved in many directions since the birth of Cocoon in 1999. JQuery and AJAX has moved much of the burden to the browser. Similarly, Node.js has made server side development easier. I found a way to easily use Node.js apps as a way to develop Cocoon 'generators' see http://warrell.blogspot.co.uk/2014/05/extending-life-of-my-cocoon.html
This provides more benefits to me than moving to 2.2 but, as they say, your mileage may vary