Power strength too important in Through the Ages
Indeed military power is important (as in the real world).  Indeed the weakest nation suffer from Aggression/War and several events.  However having the most military power is not the safest way to win a game with 3/4 players.  Most often the best players keep their military strength somewhere in between, so they can stand an Aggression/War attacks and will not lose to events but not waste all their resources on military.  Note that two player game is much more about military strength since each point you steal from your opponent is 2 points swing.

If you don't like this arm race there are few ways to reduce it:


4 players games - more players means military strength is less important.
Peaceful variant - no War and Aggression cards - just a culture race.
Through the Ages: A new Story of Civilization - the new edition decrease the dominance of some military cards, most known is Napoleon which decrease from a 3-action-pick to a situational nice leader.


Experts can handle low Military: they have ways to neglect the negative affects of low military, so that they can focus on engine building and "change gears" when time seems right.
Examples: seeing but not seeding most of the 5 events that involve military at age I, or timely seeding Iconoclasm that can remove Napoleon on the right time.  Having a effective tactic card in hand + enough resources ready for countering a War.