"Is Originality Dead In Mainstream Movies?"
Yes, because the Teminator can only kill so many bad guys in Terminator 1 / 2 / 3, before we the movie-goers, understand (or can predict) that "YES", the terminator is very good at killing, 'coz we have seen it in T1 / T2 / T3. The same applies to Batman / Superman / Spiderman, etc., etc.. IMHO, The Matrix is just awesome, The Sixth Sense is just plain lousy.
"Is it me?"
Nope, it's not you. That is just how older / "more original" story lines in movies have left deep impressions in our mind, so deep that whatever new movies which come after that are just another the-good-always-eventually-beats-the-bad movies.
That's one way of looking at it. And a slightly depressing one too as that means all forms of entertainment going forward will warrant a "meh" from myself with a "good" at best. Maybe I've been desensitised to it all and grown really cynical, lol! Who knows! :)