Now, there's no question that fencers, fighter-mages, lightly armored fighters and the like benefitted a lot from the 3.5 splatbooks. But even with just core, they're viable. Perhaps not ideal, but in their own niche, as good as anything else. Not so with 4e.
Have to rewind back to the original post, because I need to point out that this statement is utterly, hilariously wrong.
Using just core (which is the premise of your entire post, may I remind you), effectiveness of fighter mages in 3.5e ranged from mediocrity to outright putrescence. You were boxed into taking a single prestige class that had little or no flavor and that saddled you with numerous issues:
(1) You still suffered from spell failure. Your only really choice for armor was the mithral chain shirt- even leather armor was less viable than the ubiquitous MCS. And shields were wholly useless.
(2) You suddenly became a victim of MAD.
(3) You were never as effective as a single class wizard (never mind a wizard with full spellcasting prestige classes in his portfolio). They'd even show you up in the melee department once shapechange became available.
On the other hand, you would be far more effective than a single class fighter- which is like saying that winning one dollar with a lottery ticket is better than getting poked in the eye with a cattle prod.
Fighter mages in 4e are far, far more effective, and really easy to design:
(1) Start with Fighter.
(2) Add multiclass: Wizard
(3) Add Ritual Casting
(4) Add other multiclass feats to taste
(5) Use wizard of the spiral tower prestige class.
You wind up with a character who has a fairly wide range of magical abilities and still performs his duties as fighter with skill and vigor.
You have a reasonable argument (though I disagree with it), but the example you chose doesn't do anything but argue against your main point.
