Gowron's dishonor isn't because he invaded Cardassia. Gowron is relentlessly politicial. He took personal credit for the victory over the Romulans in Redemption. When he wanted to charge the Dominion on his own at the end of DS9 instead of waiting for the Federation and Romulans to protect their ships it was all about solidifying his position of power and putting himself in the position to take the credit. If there are any other honorable klingons than Worf in TNG, it's people like Kurn and Dax's revenge squad. When Ezri lectured Worf about her opinion of the Klingon Empire, she was just saying what twelve seasons of two series had shown to us.