Well, first, a Defender is a mindset, not a toolset. They care about _protection_; protecting themselves and others. Some people consider the best defense is a good offense. Others prefer to be the immovable object. That's fine. To answer the anime charge first, here's a list of Anime protagonists who are (IMO) Defenders.
1) Vash the Stampede from Trigun
Vash is a total pacifist. Everything he does works towards helping others and preventing harm. The fact that he can do this with a _loaded gun_ just makes him more badass.
2) Himura Kenshin from Rurouni Kenshin
Kenshin is another pacifist, yet extremely proficient/deadly in his chosen form. Note how many times there's a fight where others are involved, and how often Kenshin 'takes the hit' (wound or not) instead of the other.
3) Gourry Gabriev from Slayers
His entire job is to protect Lina. Last I checked, he also was a badass swordsman who no one wanted to cross.
Those are three examples off the top of my head. Unfortunately, your players seem to be reasoning backwards. 'Those guys are meatshields, and so must be Defenders.' _Even if true_, that does not in any way imply the converse is true.
For a humorous way of injecting some Defender love into them, have them read Order of the Stick, at
http://www.giantitp.com. Roy is the leader of the group, a Fighter, Yea verily a Defender of the entire party... and is quite possibly the smartest one in the group and _wholly resents_ the 'meatshield' stereotype. Alternatively, have them watch Slayers. While Gourry _is_ dumb, he's also completely badass and in no way plays 'second fiddle' to the other characters.
If they are at all team-oriented, point out parallels to team sports. Are the offensive/defensive lines in (american) football 'meatshields'? Most would say so. However, if they are not there, or in any way less proficient than those they are opposing, the 'stars' of a football team (i.e., quarterback, receivers, RBs, whatever) cannot perform.
It honestly sounds to me like you have an entire group of
prima donnas who are unwilling to share the spotlight with others. I feel for you. Personally, if none of my players wanted to play a Defender, I'd try to help them
as long as they weren't disparaging the role. If they did so, I wouldn't 'assist' their party by making appropriate encounters. I
would watch them TPK themselves, and probably show them (not tell them) that a Defender would have given them the victory.
There is peer pressure involved here. It seems from the description you have given that your players are unwilling to play a Defender _mainly due to how the other players will treat them_. You should counteract that as swiftly as possible.