I believe that you may be reading into what I said, read again and you see that I did say lighter bomb. Now, that you bring up lighter bombers, don't you think that possibility pushes the advantage further in favor of the bombers? In my first response, I addressed my concern over bombers with less fuel, less weight and needing less room (meaning: accelerated climb rate and speed). You and others that approve of the wish have mentioned light bombers by name, which I could infer from your original post may be your intent also.
That's a valid concern, but I don't think it would greatly affect gameplay. No heavy bomber would benefit from the change, while the Ki-67, G4M, Ju-88, Tu-2 and He-111 definitely would. The ki-67, for example, would be able to drop 8 city blocks instead of a maximum of 6 (perfectly placed 250kg bombs). My point is that while those light and medium bombers would be somewhat useful for city raids, they would still be leagues behind the heavies. The He-111 would be quite attractive, able to drop 16 city blocks with an all-internal bombload. But getting to alt and into strats alive in that ride would be quite a challenge, that's for sure!
Take for example a B-24 with a 16x250lb loadout, and you can take out 16 city blocks if you make two passes. Take the 12x500lb loadoud, place the bombs right and you'll drop from 18 to 24 city blocks if you can make several passes undisturbed. But the absolute king is the Lancaster with 18x500lb + 1x4000lb loadout. Align yourself with the city well, make several passes and you have the potential to take out a whopping 14 blocks in your first pass alone. If you drop all your bombload in perfect conditions you can potentially drop as many as 36 city blocks with the 18x500lb alone, and add 4 more if you've saved up the cookie. That's an incredible potential to drop 40 city blocks!
Of course, most times it's more useful to leave the cookie at base, make two passes and realistically expect to drop about 18-20 city blocks with a not-so-perfect aim. It's still leagues ahead of any medium or light bomber. Survivability would be a whole different topic...

I don't know about other players, but the only bomber I'd take more to strats if the city block hardness was reduced would be the Ki-67, when I don't have time for a Lancaster flight or there's a notable Me-163 pilot on the roster

. Well, I kinda do that already...