Larry V. often says that he is convinced the sights the Glocks come with are merely plastic placeholders for the actual sights you will install.
He did teach me a good trick to use...black out the white on the rear sight, focus on covering the lower 1/3 of the front dot with the rear "notch" and ... bingo ... much better results. Definitely works.
I always have replaced the Glock's stock sights.
Now..does this mean a Glock is not "good enough" with stock sights? Nope...ask everyone who has been shot and/or killed with a stock Glock how "good enough" it is.
All a matter of keeping things in perspective and not becoming SO hung up on the "trees" of gear that you lose sight of the "forest" of what is and is not effective/competent shooting.