Now if you play a game in which these differences in fictional position never come into play, it may be that you never notice the myriad differences between 4e fighters and 4e wizards. I assume that a lot of those who feel that 4e plays like a board game have had this sort of experience. And to them, I say: either change your game so that fictional positioning does matter; or find a different game! Because playing an RPG as a board game seems a waste of time to me.
4e classes are a "spot the difference" picture. They're mostly the same but, if you look for differences, you'll find them. That doesn't mean they're more alike than not.
But if those players go to 3E, but keep running the same scenario, what change do they get? The only difference is that now the wizard uses daily resource mechanics, and the fighter doesn't. If the only way that fictional positioning matters in play is for purposes of resource management, you are playing the sort of game that [MENTION=87792]Neonchameleon[/MENTION] upthread has called "Greyhawking". That's a type of game that many D&D players have not been interested in at least since the 1980s (as shown by the popularity of Dragonlance, despite the fact that AD&D lacks the mechanics to make it a really viable game without massive amounts of GM force via railroading and fudging of mechanics).
Not everyone wants a class with resource management. The fighter was a popular class in 3e and continues to be a popular clas in Pathfinder. Not everyone wants powers and spells. If you don't accommodate that player base they will move on to other games or not have fun.
Of course, it may be that fictional positioning doesn't matter to you, but that avoiding metagame mechanics permits "immersion" - so even though the daily cycle for the 3E wizard and the at-will cycle for the 3E fighter never really comes into play, you can still grasp the difference between them because you imagine your wizard as being Turjan, memorising spells every day, and your fighter as being Conan, swing a sword at will. This is what [MENTION=54877]Crazy Jerome[/MENTION] calls "illusionism" - projecting a fiction onto the experience that the mechanics don't themselves generate in play, but do hint at when projected via imagination onto the gameworld. There is no doubt that 4e won't support illusionism, and is in fact unrelentingly hostile to it, because of its plethora of transparently metagame mechanics.
I get fighters doing cool things.
I object to them doing cool things exactly the same as wizards. Even Warcraft does it better, with the fighter rage mechanic. The longer a fighter fights the more abilities unlock.
Which is a reason I'm not a fan of the base 4e classes: they're lazy. Just look at the Essentials assassin class for a quick example of how it could have been done better. The rely on a basic attack, but have At-wills that are situational. They have Encounter powers normally but have no Daily powers but instead have poisons that can be applied once per day. Same essential mechanic at the core, but it plays differently.
Imagine is the base 4e fighter had been able to use basic melee attacks, if they hadn't been designed to be inherently inferiour to At-Wills. Then imagine if they had to fight so many rounds to unlock a Daily via rage. Or if their exploits were just that: reactions to enemy's tactics.
I just hard a cool idea on the WotC forum involving the 5e fighter's combat superiority. Imagine if your could forge that dice, losing until until a rest, to perform a cool move. A small move and you lose it until a short rest (Encounter power) and a very cool move and you lose it until a long rest (Daily power). It's a power, but very different from spells, which is the key. It's not fighters being able to do different things that makes it a spell, it's using the exact same mechanics, formatting, recharge, and as spells that makes it a spell. Change one word,
just one word, an a martial exploit suddenly becomes a spell.
What I object is a poster telling me that, in enjoying 4e fighters, I am enjoying fighters with spells. Which is a complete misdescription of my game experience. I've never suggested,for example, that those who don't have the 15 minute day actually do have it and haven't noticed. I believe them when they say that a certain mechanic doesn't, for them, deliver a certain experience. What I then go on to do (sometimes) is explain why the techniques they use (eg wandering monsters) aren't useful to me. The analogue of this would be someone who doesn't like the 4e power structure explaining why s/he doesn't like metagame mechanics, or why the recovery cycle for player resources also, for him/her, plays an important part in immersion.
Did you enjoy fighters prior? Were you one of the many people who saw 4e and said "finally I want to play a fighter"?
If you were, it would because the fighter changed to match your play style. But at the cost of someone else. There are two players in my last Pathfinder game who I never want to play 4e with (and will never let play a spellcaster again). The kind of player who will find that one At-Will they like and spam it exclusively.