For several months after release I had an opinion that coop is not needed because C# scripting allows to create absolutely same experience within CloD standard MP mode. I.e. group coop flights with briefing, debriefing and pre-defined objectives and equal opposition.
I changed my mind because only 2 people (Banks @1ะก forum and Small_Bee @sukhoi.ru) are working on serious MP projects that can bring this possibility to reality. With so few people involved it will take too much time (13 months up till now) to implement what can be quickly done with original IL-2 coop mode. This is the reason I fully support bringing il-2 coop gui back to CloD now.
Please register and vote for this issue here
http://www.il2bugtracker.com/issues/51
(OT. Sound radar is a nasty bug too
http://www.il2bugtracker.com/issues/154 )