I also loved Johnny's appearance & demise in GTA V, but I also loved TL&D, probably more so than TBOGT & Johnny was a my favorite character from GTA IV.
I don't read Johnny's appearance as Rockstar thinking the fan base didn't like Johnny. I would read it more as a statement about how little Rockstar cares for the current fate of the series' past protagonists.
I mean, one could take the small passing mention of Nico as a reference to him being dead.
But ultimately I really enjoyed Johnny & the Lost's appearance & role in GTA V.
Johnny & The Lost MC were killed of in such a degraded way that it seems R* was trying to take a dump on any TLaD fan's face. It sure felt that way to me, I was completely bummed out by Trevor's first few missions. I just went and played through TLad for the first time in couple of years and had more fun than I did with GTAV, I'm not trying to troll.
I liked TLAD but I felt I couldn't connect with Johnny as a character. Most GTA protagonists have some traits that let you sympathize with them, and generally get to like them even though they're all violent murderers, lol. However, Johnny was just a stereotypical biker goon. That said, it was still a shocker how R* turned him into a meth-head and killed him off so unceremoniously. O_o
Still, making Johnny into a strung-out junkie when he had first-hand experience of what it did to Ashley was definitely out of character to me.
He was an enabler. A "beta male." After the chapter fell apart in LC all he had left were broken pieces and that woman. And they had quite the history. It wasn't like he was running himself literally to death for some random skank, it was his girl.