Egwene made a good war time leader because she was a sort of take charge kind of person. Rightly or wrongly she thought she should have her hands on the reins of power and she did. In war a bad decision can be better that no decision or a decision that comes too late which is what could happen if a war is being run by a committee ie. the Hall.

In peace time things are different. You want to bring people with you and convince them that your arguement is the better one. Egwene does attract personal loyalty from people but in peace time her supports will be less prepared to go and accept wild deviations from policy and as Egwene has outfoxed the Sitters so many times they would be very wary of her.

Cadsuane can see that changes are needed and she has the force of will to avoid being deflected or dragged down but she is old enought to get a hearing from the traditionalist and she has the memory of Egwene to use. Eg. "Egwene would have wanted us to ..." and calling on the memory of a great but fallen leader can be powerful.

Lastly we should not forget that a lot of the Aes Sedai are dead. There are going to be a lot less of the old traditionalist around to try and put everything back the way it was so Cadsuane may have in some ways an easier time moderanising the Tower.