Hmmm, well this is one of those movies where you need to look at it in the context of it's time and a lot of what was surrounding it, and I also think the evaluation of it's actual performance is a bit off.
For starters I will say I personally enjoyed this movie, I have it on DVD. I was also one of the people talking about hopes for a possible sequel, Salma Hayak actually produced a promotional video (shown on Entertainment Tonight if I remember) in an effort to try and raise money to fund a sequel, given that for all of it's apparent failures the movie had become a bona-fide cult classic and was apparently selling pretty well in the secondary markets. Given that this was around the turn of the century this was before companies seemed to really be paying attention to that.
That said, it's lack of mainstream success was well deserved on a lot of levels. When you put a name of an enduring "classic" series like "Wild Wild West" on a movie it comes with certain expectations. Other than keeping the names of some of the major characters it didn't really have much in common with the show it was allegedly based on at all. It's also a good example of why taking a well known character and performing an ethnic swap, especially when you turn around and bring that ethnicity to the forefront a few times, while at the same time otherwise ignoring any historical context within the setting, and well... it didn't work. When they decided to make this a "Wild Wild West" movie, with Will Smith stepping into the shoes of a well known character, it meant his acting chops were being judged based on how well he could play the role. He couldn't, he more or less played as "Will Smith as a hip cowboy" and just failed to convince you he was the character. He also had little or no chemistry with his partner, in what was very much a "buddy" production, both characters were fine on their own, but didn't mesh well, their scenes together seemed forced, and again it failed to be what the movie set out to be.
If you IGNORE that it's supposed to be "Wild Wild West" then the movie actually improves substatially, but it's impossible to forget what this was supposed to be, and indeed what the name says it is, and it deserves to be blasted on those grounds alone while at the same time being accepted as a fairly entertaining work.
Another important thing to understand is that "Wild Wild West" largely got greenlit because of the relative success, despite all odds, of "Brisco County Jr." which itself endures as a cult classic today, and despite all odds actually got renewed for a second season. The basic process at the time seemed to be that if people were still talking about that a couple years after it went off the air (and ironically became more popular after it's run) and they were largely ripping off the "Wild Wild West" formula, imagine what studios could do with a big budget, and cashing in on name recognition even if their product wasn't anything like what they were calling it. At the time we also had some serious trends towards "wierd westerns" among nerd-dom with things like the "Deadlands RPG" actually being notable successes, spawning entire series of books and becoming crazy prolific during their 15 minutes of fame. This bubble existed accross products like that and "Wild Wild West" was coming in on the tail end... which is also why there was an attempt (as I mentioned) to gather money for a sequel due to how well it apparently performed in the secondary market.
Such is what I think needs to be said here.
To be honest I'm not sure if "Wild, Wild, West" really needed a "Movie Defense Force" treatment because honestly I don't think this one was ever "universally" panned, it only got slammed by the mainstream, and always had a degree of
a following, unlike some movies which managed to fail to achieve quiet, cult-like, success. Among it's proponents it's big failure is largely in terms of not being as good as other material covering the same basic thing.
This movie also launched at least one career, that of Bai Ling.
http://en.wikipedia.org/wiki/Bai_Ling
You'll notice the differance between her pre- Wild Wild West, and post- Wild Wild West roles in terms of both numbers and the profile of the projects even if she's a supporting actress. She had been doing this stuff for 16 years (starting in 1984) prior to that movie, and did far more in the following 13 years despite her advancing age (which is a big deal for an actress).