You're not going to get a real answer here as we are just users AND I seriously doubt you'll get any real answer from Apple directly from CA., either!
That stated, there are apps that turn your entire iPad screen into a flashlight!
A blank white iPad screen is plenty bright. Like a small lighting panel.
You don't want to read it, but here it is... it is what it is.
Apple just chose not to include a rear LED camera flash on iPads for years!
Up until the 6th gen iPod Touch, no iPod Touch had a rear LED camera flash, either!
New, 2nd gen iPad Pros and the older 9.7 inch screen iPad Pros have LED flashes on them, now.
My very expensive 1st gen, 128 GBs, 12.9 inch screen iPad Pro doesn't have a rear LED camera flash, either!
Apple makes a lot of arbitrary decisions on what hardware appears on what product lineups.
Apple does what it does.
It is what it is.
If you need an iPad with an LED camera flash, sell your iPad Air 2 and purchase a 9.7ihch, 10.5 inch or 12.9 inch screen iPad Pro.