I don't see how the lead paragraphs are getting worse.  There are things in the lead paragraphs that I wish were not said the way they are.  I would love to get rid of "adapt" entirely.  However, it really isn't that far off from a core definition of natural selection.  Other than the word "adapt", it seems no different from the defintions you might read in Fisher's original work, or Sewall Wright (although, he liked the concept of adaptive topology), or Comstock & Robinson, or Crow & Kimura, or Kempthorne.  It closely parallels the definition found in population genetics books such as by Roughgarden, Hartle or Emlen, to name just a couple that were close at hand and had "natural selection" in the index.  Other texts didn't even really bother to define natural selection, but use it as individual variation leading to change in allele frequencies (Spiess, Hedrick, Lewontin, Wallace). 

 Or, is this just a wiki-turf war?