Simple answer why UFP did build more Galaxy class starship until latter

[Jason 27]

What was USS Enterprise D in practice flag ship exploration. Say that USS Enterprise D must powerful ship in fleet no evidence to back this when come military strength alone. With the way shields are design it means shield provide maximum protect warp nessal. Only place way Star Trek shields work from sides. Star Trek wound fact  Nebula-class starship  was destroy without shields speak for itself Cardassion like unable hit the ship nessal. He like made nessal simple not target pick. Nebula  class starship also has long range come to firing.

 

So one might ask why UFP build more galaxy class starship during Deep Space Nine. Safe as ship in general came to combat fact Dominion Jem Harder attack fighter destroy Galaxy class starship during Dominion first contact UFP ramming her. Rather then destroy with there weapon hit warp nessals  over came design problem older models.  Galaxy class starship carry more troops. Again Tal Yar talk about the USS Enterprise D able carry 6,000 soldiers combine normal size crew Galaxy class starship Yesterday Enterprise timeline. No reason not be the case normal timeline will. UFP will also value able having ship both transport troops and effective fighting machine Dominion call for both.