What's up with the 'mass exodus' of talent going from Blue (Air Force) to Green (Army) to become a Warrant Officer?

Opportunity. The Army Warrant Officer community is massive, so there are a lot of opportunities both technical and in Aviation.

Additionally, some of the requirements are more attainable for a larger segment of the population. Example: a 4 year degree is not required to apply to be a Warrant Officer (although, most of my Warrant Officer friends do have at least a Bachelor’s and many Master’s and more). Army Warrant Officers are “technical experts” with a paycheck to follow. Depending on years of service, a topped out CW5 retirement is only a few bucks ($128 per month) shy of a topped out LTC.

The Army’s largest WO pool is Aviation. There is an attraction for folks that want to devote themselves to becoming those “technical experts” in the cockpit with out the same political and staff progression as the O side. It still absolutely exists within the WO corps, but it is different, and the difference in the expected quantity of flight time between an O career and a WO career is enough for people to pick a path. Most WOs will trade the salute in front of the PX to the 2LT for the much greater share of flight time, specialty tracks, etc.

The WO cohort also has a different vibe than the traditional officer corps. Much more familiarity and fraternity than other denominations.

Long story short: Serving as an Army Warrant Officer carries a proud tradition an a plethora of opportunity. It’s a unique service experience, and brings a lot of reward. I was very proud to be a Warrant, and as a CPT now, I think my best leadership traits that I harnessed were derived from my experience in the cohort.

I never understood why a branch like Air Force with all the technical aspects did away with Warrant Officers??

The Air Force doesn't have Warrant Officers, so NCOs who want to go that route have to move to the Department of the Army or Navy. Also, the Air Force requires manned-aircraft pilots and some other aircrew members to be officers, thus requiring them to have a bachelors degree. As far as I know, the Army does not require Army Aviation Warrant Officers to have a degree. Finally, the Air Force requires officers to compete for leadership positions almost continuously. Just being good at a technical specialty isn't enough to get promoted beyond O-4 in general. If you're a pilot and just want to fly, then the Air Force officer track is going to disappoint you somewhere along the way. Army Aviation WOs can just fly and look forward to making CWO-4 or maybe CWO-5.