Why was the original mode of 'generating a macro on the action bar' removed by the plugin? I need to place the GSE macro on the action bar and keep the key usable after paging.

Because Blizzard changed the rules and that method no longer functions.

A macro (on your action bar like you used to do) can no longer /click a GSE Sequence. THats now called Macro Chaining by Blizzard and the GSE Sequence will cycle but fail silently. This is all described in https://github.com/TimothyLuke/GSE-Advanced-Macro-Compiler/wiki/GSE-3.2-and-The-War-Within-%E2%80%90-Catchup But the situation is what you "need" to do is no longer an option.

The alternative is to KeyBind the GSE Sequence if you want to be able to use it. This is also covered at https://github.com/TimothyLuke/GSE-Advanced-Macro-Compiler/wiki/KeyBinding Along with tips for SkyRiding.