Mostly 'cause it's not profitable. Too small a market. Same reason why business software is rare for Linux (desktop, at least): No market.
Get ready for it........Bullshit.
Linux could be the most insecure OS on the planet and still Windows would get the bigger share of malware. Simply because it is the bigger market.
How long you guys going to declare an insecure system secure because it's popular?
Tell us all about the linux servers. If they are as secure as Windows, we should see an equal number of viruses. Lots of those servers out there. But your reasoning is that no one is writing virii for them because there are a lot more windows machines in the ecosystem.
Instead of spouting microsoft fanboi swill, why don't you do a little research. Don't simply look at the desktop numbers, look at the total numbers of computers. Look at the server side of computing while you are at it.
There are plenty enough of OSX and Linux machines out there to make them an attractive target.
The reasons that Windows is used more often is that it is more insecure to start with, and for whatever reason, more of it's users are likely to enable malware that they see on a website or gets mailed to them.
You might not believe that. That does not make it untrue.
Wrong...
The argument that "Linux is more secure because it gets less viruses when there are as many Linux boxes (or more) in the wild vs Windows when you consider servers and clients" simply falls flat on its face when you consider the attack vector, infection rate, and profitability.
The part that you are assuming in your argument is that it would be just as profitable to target servers (Linux, Windows, etc.) as it is to target clients. This is simply an incorrect assumption. The difference is that very few server Admins use their servers to browse the web, download files, bank, etc. This lowers the possible infection vectors by a lot. The vast majority of virus, trojan, botnet, and other infections today happen due to user activity. Also, the majority of the profits come from either getting credit card information and/or banking information. This is the low hanging fruit of the virus writers. They have found that the best attack vector is the user through spam and malicious web pages. There just are not enough everyday users on Linux for it to be worthwhile writing for.
If you were talking about hacking, that's a different story. It does seem like hackers are targeting online credit card databases more often. The problem here is that most companies tend to not report such breaches and, when they do, they tend to provide little detail. As such, we have little idea if the majority of breaches are caused by Windows systems, Linux systems, buggy server Apps, poor network security design (i.e. there is no firewall between client and server networks), or social engineering (i.e. having someone inside).
Finally, there are iOS and Andriod users. Most people use Apps from the App Store. Presumably the App Store for both Google and Apple review the Apps before they are placed online for malicious code. You could argue that the lack of virus for these systems prove that Linux/Unix is more secure. But one could also argue that they are more secure simply because the user doesn't have root access and tend to stay within the walled garden (i.e. strictly use Apps instead of generally surfing the web and loading java apps).
