How to make a full article out of one straightforward, but interesting point? I have an interesting idea, and did a fair bit of writing and research, with some good examples to display the idea. However, I still feel like the whole paper is too monolithic, like an extended display of one point.

How can I transform the project into something with full article potential?  I’m not sure if this would require changing some aspect of the original idea to add more potential to it, or if there are some writing strategies that can be used to surround the original idea with more substance.
If you have made an interesting point and placed it in context,  you're done! There's no need to pad out the paper. Articles are allowed to be short and sweet. You may want to send it to a journal that specialises in shorter papers, or that has a section for "brief communications" or the like. Note that these are not necessarily any less prestigious than longer formats.