I have never understood how perks, unlocks, lockdown timer, spawn on SL, ability do erratic, fast speed strafing maneuvers, or the lack of learning curve for aiming & fire a weapon, historically inaccurate loadouts, peripheral indicators, killcam makes Realism more realistic than Classic. Because if you take all this and remove it, well, then you basically got classic mode.
The reason why people seems not to be able to verbally explain this - I believe - is quite simple: They enjoy Realism mode more than classic. If I were to ask on BF3 forums whenever arma is more realistic than BF3 most people would most likely vote BF3. This is not true though.I believe people get blinded by how much they enjoy something. I think its the same thing with Classic Mode.
With that say, Classic Mode is by no means fulfilled. When it comes to realism you could go a lot more further. You could
keep the Realism Mode running speed and add a system to simulate momentum (this would make movements less twitchy) and make stamina affected on surface and slope. This would make it impossible to sprint up for stairs. Slopes would affect the stamina. Rubble on the streets would affect the speed. The momentum would remove dead stops and people strafing with their guns blazing. You could keep the sway and recoil in Realism Mode and add a dead-and float zone and aiming suddenly doesn't feel like moving a cursor and there is suddenly a earning curve to it aswell as with real weapons. This would replace the extreme sway and recoil to a much more realistic option.
So really, this sort of stuff is not in the game. Stamina and speed is not affected by slope, surface, or anything, which means that players can sprint when they shouldn't be able to. Therefore I think its more realistic to force the player to move slower at all times. So Classic is definitely not some sort of Optimal Mode in that sense. It use handicaps as an option for more advanced stuff.
Regarding perks, unlocks, HUD, indicators, other aids that is simply there for accessibility - there is no point to discuss it. It does not offer anything from a realism perspective. Its simply things that the majority of people expect from a modern FPS now days. Its not tied to realism.