Please don't misunderstand me. I am not looking for any one to cater to me, or re-write code for backwards compatability. But I have seen this issue crop up in several venues related to game modding. I think it is poorly understood by both programmers and end users.
Firstly, make no mistake, Microsoft didn't stop supporting Win98 because it was obsolete, but because it cut into profits, and undercut sales of their "Next Big Thing". But this created a ripple effect: Developers of 3rd party programming languages gradually also stopped supporting it. I had an interesting conversation with a programmer in the Freelancer community, who wanted to maintain backwards compatability, but couldn't because of this issue. I do understand it.
On the other hand, in an exchange with a Simcity4 programmer (who will remain nameless),to whom I'd recommended he add a note to his (20mb) program description, that it would not run on Win98, he basically told me "Kiss off, tough s##t!". Yet another programmer, in the same community, re-wrote another Simcity4 tool, (Java-based) that would run, just for me.
Secondly, I understand the desire of programmers to move to the latest cutting edge development environments. It is exciting to master something new and create useful apps and tools. The downside - I personally know an IT professional who doesn't know what hexadecimal numbers are.
Thirdly, I suspect many modders have more recent OS's and may not have access to older machines and OS's to test on.
BUT, having said that, Simultrans has gone global. How many different language forums on this site? Is it fair to assume that all of those user have the latest greatest OS's? In my ancient formative years, I read much about what constitutes good programming practice. The most compelling lesson was, "Who will use the tool?" Is it for other (knowledgeable) programmers, or (perhaps, clueless) end users.
Now, I do own several computers, one running WinXP. Unfortunately, it is down because I did not have the same hands-on control over the OS that I have with Win98, and it got Trojanned, something I still haven't completely straightened out. I have played with Python & Blender. Lots and lots of bells and whistles. But for my simple programming needs, I still use DOS, BASIC, and HexEditor. That's just me.
So, as someone who has salivated over a new program or tool, and been dissappointed that I couldn't run it, I at least understand it. In my (negative) Simciiy4 experience, I was about the 20th user to report the same problem (cryptic log entry messages, on program abort), but the 1st to find out it was OS version related. The previous 19 were simply told they were doing something wrong and to re-read the installation instructions. (A side note: when I finally ran it on WinXP, I ran into graphics issues. Others reporting the same issues were told it had nothing to do with the code, it was the fault of the "notorious" shortcomings of a widely used graphics chip. Programmer hubris. Still, the tool, and its programmer are held in high esteem in the SC4 community, because it is a useful tool that does tasks that otherwise could not be done.)
To bring this lengthy sermon to a close, the one overriding fault I find mentioned in all the Simutrans forums is the failure of the documentation to keep up with the development. Save yourself some aggravation, add the "Requires Window version XXX" to the docs.