Regarding the two Russian A50 shot down during the Ukraine war, but it would also apply to US style AWACS.
Beside the price-tag of the plane itself, I would expect that the crews operating the radar are also highly trained, and that if it may be even harder to train a crew than to build a new plane.
I know, that something as simple as pulling the big-red handle on your paraglider harness is pretty hard when you’re in a severe flight incident dealing with G forces and the ground moving full speed toward you, and I imagine it’ll be even harder on a large plane, where you need to access a escape hatch, most likely in a burning and depressurized cabin while having no idea where is up/down due to the G-force and the rotation. However, when flying a plane which like a high value target for the opposing army it would at least feel more comfortable to know that you have a low but non zero chance to escape if you’re shot down.
Most WWII planes were brought down with gunfire, or other passive projectiles. These tended to do small amounts of damage, that added up. E.g. A plane with 2 damaged engines on 1 side, and a cut fuel line on the other, can still glide for quite a while.
Modern missiles are designed to do maximum damage over a large area. A missile hit will generally render an aircraft unflyable. The aircraft will be in an extreme tumble, if not coming apart completely.
In short, a modern plane being shot down won’t give the crew a few minutes and a stable platform to bail out from. It will be a tumbling whirl of wreckage, rapidly approaching the ground.