Right, so out of sheer curiosity and looking around, the term is used in a lot of places. And it does help an english reader to denote what is actually in the story.
An example of where both shoujo ai and yuri are used is in Citrus. So my own previous idea got shot down with demographic labeling.
Hentai is definitely used inappropriately as far as original JP meaning as well.
"Light yuri" could definitely work in the case of a manga like Citrus. However, not all stories end up like that, and there's a whole lot of "non yuri" drama/melodrama inbetween.
As far as tags go on this site, and other sites like mangaupdates, shoujo ai does help differentiate from a story going straight toward romance vs a story with complications inbetween. Same with shounen ai I suppose.
It's really weird.
In any case and at this point, I'd say it's an idea that can't really be turned back that easily. Because the effect ripples far beyond this site. Considering several other sites do use the tag "shoujo-ai", and retroactively changing it across the web isn't necessarily going to happen, I'd say it would have to stay.
Since OP also has trouble just classifying the demographic (...and I would too really), it would ultimately do more harm than good.
If something will change first, it's "hentai" as far as how it's perceived in English. And by extension "ecchi", which itself is based on "H...entai" in JP (iirc). Both seem pretty much set in stone. I'd imagine it's very similar to shoujo/shounen ai now. They will continually mean something very different from what the terms would mean in actual JP.