Aw c'mon, you can't tell me that you don't know that Financial is winning every "most favorite trait" poll in this forum, for years.Examples are here, here and here, you can probably find lots more if you dig a bit deeper in the forum search. I think I even remember one poll where Financial was excluded because the poll author expected it to win anyway and therefore "pollute" the ranking of the other traits.
The fact that some high-end players believe that it's overrated doesn't change the fact that it is (as Turquoiside states) the most popular trait on these forums, pretty much from day one. It's a also a very versatile trait that runs well with many strategies, and (imho) is indeed one of the best traits up to Emperor difficulty, for single player games. It loses its appeal at the highest difficulty levels, where the AI gets insane bonuses, and having a bit more trade doesn't provide much of a benefit to the player - but at these levels, Civ becomes a very different game altogether, and most forum members can't or won't enjoy to play those. In multiplayer, it's obviously less poweful as well because it doesn't provide any direct bonus to the military, which is the focus of multiplayer gaming. But for the games that most Civ players play - single player games up to Emperor level -, Financial is indeed one of the most powerful traits.
I concur. Very well said. A one commerce bonus may not seem like much, but early to midgame, if you have the right tiles (a start with heavy seafood, for example), it can lead to the start of a significant snowballing tech lead pre-Pottery, and being first to BW opens up a lot of options.