I have no problem with BIFTs. I find them useful for players who aren't good at, or just struggle at, roleplaying. Some players make choices when they create their character as to how that character will behave. But once the campaign starts, they inadvertently revert back to their own personalities. We're not all professional actors (or voice actors like on Critical Role), so it's not always easy to "stay in character," and it can be nice to have a reminder jotted down on the sheet to jog one's memory. And, like a lot of things in D&D, people who don't want or need them can simply ignore them.
And as for them being too narrow and restrictive, the listed BIFTs are just examples. If you choose to utilize them, you are free to roll on the provided tables, pick the ones you like, alter the listed ones, or create new ones of your own. It even says as much in the PHB on the righthand side of page 123 in the section titled Personal Characteristics.
I don't understand why people keep wanting the get rid of aspects of D&D that aren't mandatory, but are just tools to help people who need them. Unless it comes down to freeing up page count in the 2024 PHB for other things they want to include, I see no harm in leaving them in.
The upcoming Planescape book mentions 2 new player backgrounds, so it will be interesting to see if they include the BIFTs in those. Strixhaven had Personality Traits, but it replaced the Bonds, Ideals, and Flaws with Trinkets.