You're a sword and board user who does not benefit from Dex for attack and damage most of the time. But, you're one of the fighting classes, so you almost certainly have a high strength. IE, you almost certainly have a lower Dex in exchange for the higher Str.
The rogue ability depends on making your Dex save to begin with.
Yes, you have the shield bonus to Dex saves now, which helps. But, odds are you still don't have a high enough Dex bonus to depend on the Rogue-like ability to begin with. Only in the unusual cases of a PC who happens to have both a high Str and a high Dex would it be a genuinely rogue-like ability in practice for that PC.
It's not something you'd take as a feat itself. You'd probably prefer the Resilient Feat instead, if that were the purpose of the feat. That way it continues to go up as your proficiency bonus increases over time, and the other benefits of a higher Dex will come as well (such as initiative, and some skill checks).
It's just...not why people were taking this feat. People were taking it to do something with their bonus actions with a fighter-type, when they had decided to go with the (otherwise sub-optimal) sword and board instead of the big two handed weapon and/or polearm and/or duel wield or Dex fighter. There are ways to use your bonus action with each of those types of builds, and now the bonus action option for the sword and board guy is frequently useless (or even harmful, in a party of ranged attackers beside you).