I like Albert
I'm rewatching the show for the first time since my childhood and I'm on Season 5 now. I totally get why they wrote Albert in as a permanent character. His actor is really good and convincing (his line delivery is just spot on lol) he has an adorable face and I think Albert adds a fresh angle, he grew up differently than the other kids, has different morals (being okay with cheating Pa and Jonathan, lying about being an orphan to get a dinner and warm bed with Andy), and learns a lot through the others while also teaching them a thing or two (telling Andy he won't fight him because they're friends and writing bad grades on purpose to make Andy feel better! so cute)
I know there's people who don't like him/him being added, but the show is already very far removed from the real life of the Ingalls family that it's a change I don't mind. It's also obvious even through their on screen interactions that Michael Landon really must've liked Albert's actor, it makes for a good father-son chemistry in the show.
(Of course it's also obvious that it serves Michael Landon's Christian interest of having Pa teach a poor orphaned boy about God and lead him to live a honest faithful life... but that kinda comes with the show lol.)