Now, evolution is often understood as a ladder of progression – from simpler, basal organisms gradually becoming more complex and sophisticated.
This view of evolution is entirely incorrect. Species do not transform into other species. While "simpler" and more ancient lineages of organisms may indeed resemble their ancestors, they are nonetheless derived from common ancestors with their closest (and furthest) relatives. I.e. they do not represent members of a group which have transfigured into something more complex.
However, the below ad is very cool – despite the erroneous depiction of evolution. Let's face it, it's really about the pen being able to create and erase. Unwittingly, it does draw out a good point about evolution: throughout evolution, features (I'll say structures for the sake of simplicity, but there's a biiit more going on at the genetic level) are gained AND lost.
"Simpler" does not necessary mean more primitive. Many cave-dwelling organisms are colourless and blind, while their relatives in sunlit environments are colourful and may rely on vision. Fish are a good example, as cave fish have eyes, but cannot see. These apparently simpler fish are more derived from ancestors with functional eyes and are no less derived than their colourful counterparts.
And "primitive" doesn't mean less adequate. Primitive organisms are those which are older or resemble the basal ancestor of a group of organisms more closely. A primitive organism is usually just as well – or better – adapted to its environment than more derived or apparently complex species. Hell, if they've been around for so long, they must be doing something right!