Namekians strictly consume water, so them evolving to develop breasts to feed the especially young when they cannot via storing water in them wouldn't be that farfetched.

And while yes, Namekians do develop far faster than humans do, Case in point being Piccolo Jr. Being 3 years old in his arc despite his adult appearence and maturity.

However, Kami is visibly old when introduced, And his age, From the point when the nameless Namekian split, to when Kami is introduced, would be 292. Presuming Kami is in the namekian equivalent to a human at 40, we can simply multiply this number by two since the average human life span is about 80, giving us 584.

Now, let's say all namekians live in this time frame. Back to Piccolo, Piccolo Jr. Matured from infancy to adulthood in the span of 3 years, 7 times faster than a human.

By making namekian babies about as weak and pathetic as human infants, we also force them to rely on their parent's presumed breasts for feeding, slowing down their maturing process.

Therefore, by doing this, we also simultaneously slow down the aging of namekians, making the 584 estimate multiply by 7 to FOUR THOUSAND, EIGHTY-EIGHT YEARS.

In short, namekians would live longer if they had tits and used them. Thank you for coming to my ted talk