The level bomber class was only ever introduced for scenarios, like say the time in Normandy when the USAAF slagged the enemy defences preparatory to the assault. (And dropped short, killing a general, IIRC). or for a modern scenario with an Arclight strike on tap.
They are pretty useless things that just goto x,Y roughly and offload some unaimed big eggs then wander off. Probably the least useful class in the game and only as I said - I included them for historical use only. Pretty worthless outside a scenario where they are pre-planned as they have a 12 or so turn delay (and that should probably be much more).
But, having the class available meant that some of our OOB design team way back when just
had to have squillions of the things in there "just because". Waste of perfectly good OOB slots IMHO, any OOB really just needs a few representative bombers on the off chance a scenario designer wanted to use them. Worthless things for the regular player, and looking back, why did I bother
!