It's not the same thing. BG1 has a "table-top with a not very creative DM" feel, while DF and Tyranny feel like a bunch of 15-year-old teenagers playing in the kiddy sandbox, trying to be mature. DF is Joss Whedon-esque, complete with smarmy "witticisms" and one-liners. It's what young, not very smart Americans steeped in modern popular culture would make and oh, boy, does it show. Tyranny exhibits this perfectly, the writers don't have a clue what they are writing about and don't have enough/varied life experience to do such a heavy topic justice, and the end result is apparent.
BG1 is also not immature, it's a reasonable campaign and the writing doesn't grate most of the time. It might not be all that good, but it isn't cringe-y. It doesn't try to tackle questions of colonialism, evil, the psychological and economic consequences of war, justice, personal responsibility in a seemingly unjust system, and whatever else they tried to do with DF and Tyranny.