Thanks for linking real research, but your studies don't support your claim.
The McCollough and Reedy papers showed that diet does make a difference in life expectancy, but they said that adherence to any of a number of different healthy dietary guidelines had nearly the same effect. The diets tested were high in "fruit, vegetables, whole grains, nuts, and legumes," but they also permitted moderate amounts of meat and low fat dairy. (In fact, the only kind of meats the dietary guidelines avoided were red and processed meats.)
The Fraser study used Seventh Day Adventists as the study group. Some Adventists are vegan, but others are lacto-ova vegetarians. All are supposed to eat a balanced diet and avoid gluttony.
The conclusion of the Martinez-Gonzalez study states, "Among omnivorous subjects at high cardiovascular risk, better conformity with an FP (food pattern) that emphasized plant-derived foods was associated with a reduced risk of all-cause mortality." There's nothing vegan about this study; it suggests eating more plant based foods has a positive correlation with mortality even for those who don't want to become strict vegetarians.
Now maybe there is some research to support a vegan diet, but these studies don't do that. They do suggest that making fruits, vegetables, whole grains, nuts, and legumes the core of a well-balanced diet is important.