Except that's the way professional CAD packages do it, for example.
You keep mentioning CAD software, but there is no similarity between CAD formats and typical raster formats. JPG, PNG, TIF, and GIF are industry standards that GIMP should be able to open and save. CAD formats have vectors and a lot of other information that is particular to each software's implementation since there aren't open, widely-used vector file formats.
There are AutoCAD-compatible clones that open and close that proprietary format without question. LibreOffice also opens and closes non-native formats without complaint if you turn off a checkbox preference. If you stretch the analogy enough, we can take this illustration to even further ridiculous extremes. But the fact remains, GIMP is raster software that can be used to edit lots of standard format raster files that shouldn't require exports for files opened.
If you honestly believe Export is the correct terminology and UX, then you should also be advocating GIMP's "Open" menu change to "Import." That would correctly match what you are claiming on the save side. Open would then be reserved for XCF files but everything else should have to be imported. GIMP should treat the whole business like RAW and refuse to ever save any changes over the originally opened file unless it is an XCF.
At least that would be consistent. Insane, but at least consistent.
The current GIMP behavior appears to be structured to sell the software's (developer's) capabilities over users that are too stupid to think for themselves. Unfortunately, everybody sees this except for the developers.