When I get to Venus Era I may change some defense buildings to ones having attack. I do not know. By that time I get to Venus I know Jupiter will be old news. and a further Era may already exist beyond Jupiter. Thus I may be sticking with the importance of defense yet.
As far as initiative.. yes initiative is very important. as I wrote too. just not using that word. However when one cannot use higher initiative troops than the enemy, defense is critical. as I wrote.
To say defense is critical is not to say it is all that matters. A balanced approach is the best and what matters. Planning a couse where one has only one plan, one option is not good. making one thing matter is not good. having multiple options is better. and most of all doing what you like, thinking through and doing what you think is the right way to go for your own play style is the most important of all. To the op here, do not just slavishly accept what I wrote. Think it through. and do what you think is the right way for yourself.