Why not make a 30.06 assault rifle?

The debate rages on over the stopping power of of the 5.56x45 NATO over the 7.62x51 NATO much like the .45 acp vs 9mm argument. So I thought, why not have the best of both worlds and make a modern assault/battle rifle chambered in 30.06? Much like the Coast Guard choose the .40 cal over both the .45 acp and 9mm handgun round. The 30.06 has proved itself for 100 years to be an effective cartridge at stopping pretty much anything, and even some troops during Vietnam were still using the M1 Garand.