By saying you want reb at atrocious for guards, you´re also saying you want insideplayers to be really heavy on rebounds.
If you have guards with reb at say 7, you pay a lot of salary, but you can get it back on the insideplayers.
Ideally you would like all players to be roleplayers, perfected for the tactic you´re about to use.
For example, say you have a SF that you like a lot. He defends both outside and inside. And he´s perfect for an inside offense, but he is not a very good rebounder.
If you play him alongside two guards with Respectable rebounding, the total amount of rebs on your PG/SG/SF vs your opponents REB on the same positions will in many cases come out in your favor...
If you instead have a Sf with high rebound, you might have a PF or center with lower than normal reb that you can use to get the most out of your tactical choice.
But this might be more important in the future as more and more thought is being put behind training.
As long as your opponents has atrocious Reb as well you won´t see the value of reb on guards, I guess....