I think, the problem on many devices like my old TEAC 12/10/40 was, that after let's say burning with 8x and then verifying , the drive didn't spin up to its max. speed (even with a perfect burn) but read with the burning speed, so in this example only 8x, which was quite boring. With ejecting and reloading this would never happen.
But, (what I remember) Nero introduced this feature first in 5.5.9.0 (with 5.5.7.2 the CD-R was always left in the drive).
Interesting: My new LiteOn LTR 40125W would eject/reload using Nero 5.5.9.0 , but doesn't anymore with 5.5.9.9. and always verifies with max. speed!
So, finally, the ahead guys seem to have found a intelligent algorithm (depending on the device), whether this 'feature' is necessary or not.