This phenomenon can be (and has been) described as regressive evolution (the loss of a phenotypic trait). There are several reasons why this occurs:
Neutral mutations which become fixed through genetic drift.
Positive selection of regressive mutations that are beneficial.
Pleiotropic antagonism: positive selection for one trait may have the consequence of ...
Short Answer: No, the appendix is still considered a vestigial organ.
Long Answer: The idea that that vermiform appendix is vestigial originated when Kumar et al (1989) removed it from the body, but failed to find any side-effects. From then on, it got widely established that vermiform appendix is a vestigial organ and has lost all its functions during the ...
The appendix is a vestigial organ.
According to the Oxford Dictionaries vestigial means:
Degenerate, rudimentary, or atrophied, having become function-less in the course of evolution.
This doesn't mean that a vestigial organ necessarily has to have no function at all, as in the case of the vestigial wings in mutant fruit flies ...
From this article I quote
Hair in the nose is one of the body's first lines of defense against
harmful environmental pathogens such as germs, fungus, and spores.
Another purpose for nose hair is to provide additional humidity to the
inhaled air. As the air passes through the nasal passages, the mucus
and hair provide heat and moisture. ...
Yes there are several published sources (with photos) of whales born with protruding vestigial legs.
Modern Right Whales have rudimentary legs--completely inside their bodies.
"approaching the inquiry with the most skeptical ...
One easy way to make an animal faster (especially if it is larger than a housecat), is to make the ends of the limbs lighter, the more mass there is near the end of a limb the more energy it takes to move it and the slower you can swing it, that translates into moving slower because you cannot get the limb back into position for the next step fast enough.
It turns out that the vermiform appendix is NOT a vestigial organ based on Darwin's definition.
Without rehashing what the appendix actually does, I'll quickly address the faulty arguments that it is a vestige.
Point 1: Darwin called the appendix a vestige because it was a remnant of a larger cecum used for digestion:
RESPONSE to Point 1: In most cases ...
So-called "vestigial" features are defined in a post-hoc fashion as features which do not have a positive correlation with a population's fitness under its current living conditions. There are no special names for the evolutionary processes that lead to their loss, since they are exactly the same evolutionary processes that act upon any feature that has a ...