I would add:
For great part of World, computer donations are gold mine and run with 98 (or 95), so If not say stupidity, it's run with Internet Explorer 6 and it doesn't support PNG ... However, internet using is rare for this kind of computer.
In other words we lose the advantage of PNG's alpha color!
It seems negligible but it is the hidden face of the iceberg.
"The normal lambda user" use what is provided instead of choosing another browser or just a free OS ...
It is rare to give window license or other old software and we don't know if this legal about law... and I'm sure you have old keys win95+ that you don't use, and more.
Same thing for old hardware that can transit by boat .. . It's not good for business, but I am not the arbiter of your conscience, and Bill Gates gives already millions $ to foundations, tax or not...
We do not even know if there are famous foundations to give our old licenses and other...
IN SHORT, everything depends of project and do not forget this part of the World, compatibility may be essential!
Like AHK , it can use on win95 +, and giving very old versions of software:) and open source!
Do not forget the forced way of PNG because the GIF owner is bankrupt and they was a "Request For Comments" will trigger PNG to ISO standard! Today, we use may not be using PNG without all this events ...
At the end, image format is into a good case, when we see audio format only WAV codec is supplied (and outside Europe WMA, Due to blockade of WMP but old OS haven't WMP) same thing for video ... but ogg and h264 are awsome ...
I can not count the times I had to install basic codecs MP3, AAC, OGG, DIVX, XVID and H264 for friends ... it is incomprehensible how the interest of money has limited computer and internet ...
My reply is out of this thread, but to justify the choice of GIF, even if GIF must disappear as soon as possible.
Edit: It's possible to have a world map about autohotkey downloading and acces to forum ?
[Moderator's note: Splitted from Any free resource teaching how to make gif files? as it becomes out of topic]