I have noticed that most anime characters are drawn without lips. Is there a specific reason for doing this?
I have noticed that most anime characters are drawn without lips. Is there a specific reason for doing this?
The reason seems to be more historical and technological than some kind of art or costumes. Realistic lips are hard to draw. The lips has certain singularities that prevent creatives from trying to imitate them. In cases where they need a close up (focus on) the lips, the quality/relistic could be increased (this depends greatly on the production) but in most of case whereas there is another more important elements in the scene, some realistic details are just dropped.
Of course, some technology could allow producers to pimp up all realistic features (lips included) so they picture more realistic lips.
In a single line, the answers is: if they are not pictured, is because it results a pain to produce them; if they are pictured is because all other details are also realistic, why not lips.
This sort of lack of defined lips is stylistic within the art form of anime (and some manga do this as well). This isn't something that the artists can't be bothered to draw due to lack of talent, skill, or time. Even though that style exists, many anime character designers and mangaka have drawn lips in their character designs, from the earliest anime up through today. So we can be sure that it is not that lips are just too darn difficult, or that only the early artists could handle it but that newer generations just aren't cut out for drawing lips. Those who do not incorporate well-defined lips into their character designs desire for their designs to look that way; it's not a case of refusing to learn how to draw a face accurately. In the same way, we can note that some anime characters have barely-there nose design, but this is because some artists think this looks better than drawing out a large nose or detailing nostrils, rather than because they couldn't draw a more robustly-shaded nose if they wanted to (and likewise, some character designers and mangaka do choose to draw very defined noses compared to what other artists prefer).
Furthermore, one might even be hard-pressed to prove that anime characters are "usually drawn" without lips. Two out of the four images you posted as examples actually are drawn with lips (the Full-Metal Alchemist image does not look like it comes from an anime cel... but it does have a lower lip in the illustration). So this may not be the most popular answer to your question -- certainly a lack of visible lips is true of many series -- but whether it is true of the majority of series (in other words, "usually" the case) is debatable.
Historically, both shounen and shoujo anime have featured lips on a regular basis in the character designs for both male and female characters:
http://www.new-anime.com/images/black-jack_3.jpg
Yet recent series have also featured a good deal of defined lips...
http://animemvc.com/Content/animes/nana/nana_hachi_komatsu_nana.jpg
Some series have characters who wear lipstick as part of their personality...
... or as a plot element:
In series in which characters' lips are not usually emphasized, the shape of lips is often seen in side views...
... but even in such series, at times the characters' lips are drawn in detail, in order to emphasize that the other character in the scene is noticing their lips (worrying about getting kissed, thinking the other person looks alluring) or to contrast a female character as young and demure against other characters.
Animes are hard to make and the majority reason for creating Animations is to express imagination, creativity, ideas etc and not how good you are at drawing real pictures.
If you draw real lips, would have to show teeth as well when the characters smile, which further adds to the complexity without substantial visual benefit for the viewers.
Dont you think the without lips version looks cute ?
A lot of traditions in anime design come from manga. This makes sense: many anime are adaptations of manga, and so the makers of the anime usually want it to resemble the manga that's being adapted.
In the case of manga, this tradition comes largely from the fact that drawing lips requires intricate detail in a very small space. Aside from being more difficult to draw than a simple mouth line, lips also take a lot longer to draw, and manga is often drawn on a very tight schedule. As a result, they're generally not considered worth doing for most characters: specific situations or designs might call for them, but if that doesn't happen, the default is to leave them out.