Writers usually divide their works based on word count into flash fiction, short stories, novelettes, novellas, novels, and epics. Now these aren't one to ones when it comes to game developement but it's a much better tool to describe games then what we're using now.
For an example many of author's games are better described as flash games (not that Flash just flash as in very short), while something like A Short Hike and many would be a novellet (gamellet?). Many arcade 8 bit, and 16 but games would fall somewhere in between flash and short. Many AAA games and many RPGs would be Epics. Etc.
Of course this isn't a perfect way to categorize games but it's certainly better then the term small/short being used for anything that's less then a 100+ hour AAA game and it could help developers too. You can ask yourself "Do I really want to make a Epic? Or maybe this would be better as a short or a Gamellet?" or if you just want to make something very small you can just say "I'm going to make a flash game."
Different names are needed but I still think the point stands. We need a different to talk about game length then just the words short, small, or long.