Sword of Spirit
Legend
If you feel that strongly about it, then I encourage you to add sorcerer domain spells at your own table. This edition, above all others, comes with a strong recommendation to make the game your own.
My current personal solution saves me that detail level of effort, though it is a more extensive fix (I have about 3 points in the class that I needed to address: 5E - Sorcerer class improvement house rule), but if there were an official fix that were "good enough" I'd ditch my personal solution so I'm playing the same thing as everyone else playing the official rules.
One of my main unstated points (that some others have directly stated) is that they have kept periodically adding "domain spells" to UA sorcerer subclasses for years now. It's like they're testing the waters...for what? I think they're hoping people will say, "Yeah, we like giving free spells to just these new subclasses" - because then they can do what they likely realize they probably should have done from the start, but without going against the "no revision by errata" principle.
Maybe they think that the majority of those against giving this feature just to new subclasses are going to stop following UA articles, and the newer more casual players brought into D&D since then aren't going to care that these new subclasses do something different than the PHB. Maybe they're right, I can't say. I'd lean towards that not being likely though, since I'm guessing that many of those who provide feedback to UA, new or old, generally care about things like balance and not obsoleting the design of a core PHB option when possible.
The "enough is enough" sentiment is because, as @Li Shenron well put it, they keep "sneaking it into new UA articles". They should just stop that and revise the existing sorcerer subclasses to have bonus spells--probably through a class variant enhancement (pure upgrade) feature. It will likely be one the most popular variants out there.