The AT&T-exclusive Lumia 900 is one sexy slice of smartphone. After the iPhone, it’s the single most unique and alluring physical specimen on the market. True, its AMOLED screen isn’t quite up to snuff compared against today’s 200- or 300-dollar Android flagships, but — at a meager $50 on contract — Nokia has definitely nailed the hardware side of things.

Unfortunately, the Finnish company’s stupid controversial decision to attach itself to Microsoft’s Windows Phone platform has not fared nearly as well. Indeed, that choice of operating system is seen by many industry insiders as the number one reason why Nokia continues to fall out of favor with global consumers. Reuters reports:

“No one comes into the store and asks for a Windows phone,” said an executive in charge of mobile devices at a European operator, which has sold the Lumia 800 and 710 since December. …

“Nokia have given themselves a double challenge: to restore their credibility in terms of making hardware smartphones and succeed with the Microsoft Windows operating system, which lags in the market,” the executive said. …

“If the Lumia with the same hardware came with Android in it and not Windows, it would be much easier to sell,” he said.

I would say that sounds like a pretty damning excerpt, except for that reality’s been pretty obvious for a while now. Back when Palm was actively looking for new ownership, I figured Nokia would make a go for webOS and Palm’s beefy patent portfolio. To me, even in retrospect, that would have been a better course of action for consumers, and a Nokia-built webOS smartphone would have made pretty big waves compared to the lackluster management HP brought to the table. (The Verge’s Joshua Topolsky even decries Nokia’s exclusive partner OS, saying in his otherwise positive Lumia 900 review that he thinks “it’s time to stop giving Windows Phone a pass.”)

But this isn’t about Palm or webOS or HP; it’s about Nokia and the future merits of its Stephen Elop-backed all-in bet. What can the handset maker do moving forward? Well, nobody knows the true details of the company’s game plan, but according to Reuters,

Nokia is trying to capitalise on its closer ties with the operators and to exploit their irritation with Apple’s dominance and Google’s bandwidth-hungry services like YouTube in the hope they will push their phones on the market.

Coupled with some U.S. carriers’ plans to reduce their subsidies of Apple’s iPhone, Nokia might still have a(n admittedly gimpy) leg to stand on. Says iDownloadBlog,

The Lumia 900 has seen some modest success in the United States. AT&T has backed the device with a nationwide advertising campaign because Microsoft funneled millions of marketing dollars to carriers as part of its agreement with Nokia.

The Lumia 900 launched as an AT&T network exclusive on Easter Sunday, when most AT&T stores were closed.

But in spite of its incredibly cheap $50 price tag and Microsoft-centric blogs running polls claiming that most people switching to the Lumia 900 are moving from the iPhone and Android, the handset has already fallen off Amazon’s best-selling list after briefly topping the online retailer’s smartphone rankings.

Still, however Nokia alters its future approach, it’s pretty clear that awesome hardware itself no longer matters as much as the OS that comes preloaded on it. By all accounts, Windows Phone 7 is a good year behind iOS or Android for feature support, and app support isn’t anywhere near acceptable compared to those two market leaders.

Here’s hoping Nokia can get back to its N95 glory days.

But without a time machine, I just don’t think they will.