It depends on what your goals are
If your goal is "perfect conformation," then no.
If your goal is to produce "dogs that win more than they lose," then it depends.
What it "depends" on is whether that dog has any TRULY OUTSTANDING "other" traits that are uncommonly good
For example, my entire bloodline was based on Ch Hammer, who was a squat, ugly little thing with bad hips and bad stifles. But Ch Hammer had a level of gameness WAY beyond the average dog (as game as any Hollingsworth dog dreamed to be) ... and he was as tough (or tougher) than any Hollingsworth dog ... and he was also incredibly smart and pit savvy ... WAY beyond the average dog (and ANY Hollingsworth dog ).
Ch Hammer was almost always "bottom dog" (because of his defects) ... but his strengths were so outstanding that they still carried him to victory 3x over "better built" dogs than he was. Ch Hammer was so tough, so game, and so slick that he would literally maneuver himself out of harm's way from the bottom, and he was so relentless that he would have his opponents trying to jump ... even though they were on top of him ... and Hammer would spring up off his back when they did and drag them back into the pit
Therefore, even though breeding to Ch Hammer hurt the 'conformation' of my Hollingsworth dogs, the level of gameness stayed true ... while the level of intelligence was dramatically increased ... and so consequently these dogs won more than pure Hollingsworth dogs did. My dogs have always been plagued with stifle issues, here and there, and yet they regularly still beat dogs that have better stifles than they do. Again, this is because they have other traits that are truly superior to most lines. Most dogs of most lines do not have the heart or intelligence that my dogs do. A smart game dog will almost always figure out a way to win, while a dumb not-so-game dog will find itself in a bad spot eventually, put there by his savvy superior, and when he is unable to figure a way out of it ... his lack of gameness will result in a 10-count. Been that way for 2 decades now
So, back to your dilemma: IF the dog(s) you're talking about have some other key, physical advantages over "the common dog" ... that you can depend on ... I would happily breed to them. Again, been doing this for years, and been beating dogs with "better stifles" for years
Because the GREATEST "malformation" in a bulldog is an improperly-developed heart or brain
But if the dogs you're talking about are just average schmucks with good pedigrees, with nothing "extremely good" about them, then I wouldn't waste my time breeding them (good stifles or not). And that is performance-wise.
And if conformation is your main goal, then no, I wouldn't breed them either.
But if you have a dog like Robert T, or Icon, with "straight stifles" ... but that will out-hustle, out-maneuver, out-muscle, out-think, and totally whip anything its weight on other key traits ... then I wouldn't care what their stifles looked like ... because the proof is in the pudding
Good luck!
Jack