The mod may not have errors. Sometimes, the act of installing a mod can cause errors, either by a mistake on the part of the installer or a conflict with an existing mod.michaelo wrote:"Also if the MOD causes a parse error"... you fix it! Why would you install a mod with errors in the first place...
In the past five years of writing and supporting mods, I have learned an important thing about mod users: most users are not programmers. There are exceptions, like those of us in this thread, but the general end user is someone that doesn't know the difference between if() and array(). If anything goes wrong with an install, these people have no idea of how to fix it.
If two mods are installed in the same area, they would not know how to add or modify a conditional, on their own, to create a situation like if(MODX && MODY). They would need specific instructions giving them the code to add in that case. That shifts the burden to the mod authors. Authors cannot be expected to test their mod against every other mod written (there are already over 120 in development on this site alone!) and include alternative install instructions for every situation where a conflict may arise. If that was required, no mods would ever be released.
IMO, the best approach when coding a mod is to make things as simple as possible for the mod user. I'm all for minimal changes to core code and adding on/off options for major mods that are largely standalone files. I try to do that myself in my own mods. But, if it overcomplicates the install for the end users, it is not useful.