Good point but considering the likes of FF, Street Fighter, Mega Man etc. and even dynasty/samurai warriors are all well into double digits (screwed up chronology/numbering aside) ES run is not so bad.
But I'm not overly disappointed that they aren't working on a 5th game, Oblivion did end the series quite nicely, and although they could obviously go back and revisit the universe, I'd prefer to see them working on something else. Why is Halo the only series that gets bashed when it's announced they're releasing an expansion for one of the most popular games of all time, yet a 5th Elder Scrolls game, not counting spin-offs and expansions is what everyone wants?
I say give the series a rest.
Also, am I the only one who liked Oblivion more than morrowind? :( Yeh it was dumbed down but for some reason I found it way more enjoyable.