Some interesting theories posted here about why publishers of successful games over time fail trying to release successful iterations of those titles.

Mine is simple. Yes the old ones who designed and coded the originals have retired. The new production execs and devs above all else want to make a name for themselves in the industry by creating something new and original. They consider working on a new version of an old title, low status and something that will not further their career, the choices they see are:

* Just use the original title but create a completely different original game hoping they stand out for having a creative original idea.
* Avoid, postpone or negotiate to publish something else they have original ideas for
* If top management insists, do it grudgingly, not caring about the quality, just as fast as possible to get it behind them.