Some possible counterarguments:

1. Mathematics is a lot more abstract than it used to be.

2. Mathematics is a lot more specialised than it used to be.

3. Non-mathematical content is inaccessible to those who don't read English.

4. Space in academic journals is too precious to waste on inessential content.

5. The style is part of a universal mathematical culture so you should fit in.

6. There are many alternative places to publish nontechnical academic writing.