Look, I agree with some of your points, but the fact is if strategic bombers were to be made realistically it would have no point. Only the UK and USA developed strategic bombers (unless you want to include Germany’s long range sea/recon bomber the Condor), so to make them entirely realistic would only allow two nations to buy and use them.
If you want to, think of it this way…
Fighters: Single engined air superiority fighters such as Spitfire, Mustang, Messerschmidt, Zero, etc. Used in A&A primarily for defense and mobility
Tactical Bombers: Single engined fighter/bombers such as Stuka’s, Val’s, SBD Dauntless, etc. Used in A&A primarily to attack in combined arms with fighters and tanks and for mobility
Strategic Bombers: Any heavy bomber, both strategic and tactical, 2 or 4 engine. Everything from a B-17 to a Heinkel. Used in A&A for mobility and all around attack.
Your proposition, while historically accurate, would weaken the strategic bomber and render it useless. The unit as it is in A&A represents far more than simply a strategic bomber, consider it a misnomer, it is both a strategic and tactical bomber whereas tactical bombers are really fighter/destroyers or fighter/bombers.