How many points should a journal paper have?
I'm going to take a fairly strong opinion here and say that every paper, no matter how large or how small, should have precisely one core point.

That one core point may have as many or as few lines of evidence in support of it as are needed given the research context: that will be very dependent on the particulars of the paper and the community to which it is addressed.  Everything, however, should support the one core point, whatever that may be.  If you organize a paper otherwise, then in my experience both as writer, reviewer, and editor, it will tend to result in a paper that is poorly focused and scientifically weak.  

So if you find yourself wanting to make multiple points with a paper, I would recommend considering the following two questions:


Are these different points really different aspects of the same core point?
Should this really be more than one paper, with different papers focusing on different core points that require different lines of evidence?


In the case of a new language, for example, there must be some key motivator for building the language, which is what you want to highlight.  At the same time, a new language will be much less mature and well-developed than many existing languages, and so there are certain to be aspects of comparison where it will show up poorly---but which may not matter.  The question then is this: what is the important thing to be learned, relative to existing pieces of work, and how do you provide evidence supporting the notion that you've done this better than existing languages and yet not introduced fatal flaws in other aspects.