Obsidian makes games that I tend to like better every time I play them. Their games have bugs, but Bethesda is every bit as bad in that department. Obsidian is just behind BioWare right now as my favorite developer, though at this point they are the better RPG developer. They make choices matter. I hated Fallout 3 and was apprehensive about giving New Vegas a try, but some things convinced me to play it. One of those was the faction system, which is something I'd always thought Oblivion needed. When the very thing I'd been asking for actually showed up in New Vegas, I was ecstatic and bought the game and adored it. I've now played it four times and do love it more every time I play it.
As far as writing goes, I think they are great. I'm not going to say you're wrong, because there's no objective truth to such a claim (nor the reverse). But Knights of the Old Republic II is, to me, the definitive Star Wars story. It is so intelligent in the way it subverts the lore. It takes the dei ex machina of the Star Wars universe and twists them. Kreia is the best character in video games and in the Star Wars universe, but I think much of the rest of the cast is good too. People want to write off Atton as the Han Solo or Carth Onasi stand-in of KotOR II, but that is so untrue. His backstory is grim, and it's something he still struggles with. In fact, it is something you can convince him to embrace. Visas, Brianna, Mandalore, and Bao Dur are on equal ground as Atton.
I love Obsidian because they truly get how to approach games as a storytelling medium. They understand choice, both in terms of story and in character building. And they are ambitious. They can take overdone properties like Star Wars and make them seem new and fascinating again.