Exceeding the CDR tends to stress the battery. Stressing the battery damages it and lowers its performance potential for future use. Once you've pulled excessive power from a battery, you no longer know what it's capable of doing.
3.2 v is the standard figure for that calculation because it's at or slightly below the limits for most
mods and saves you the trouble of finding out what the limit for that particular
mod is. As you say the limit for the Aegis is 3.26 v, I agree that it would be perfectly reasonable to use 3.26 v instead of 3.2 v. The difference is two watts - 88 w, rather than the 86 w I initially calculated.