Wait, so a paladin can't be defined by a narrow ethos?? I'm sorry 4e must have not gotten that memo either since some of it's paladins are defined by a "narrow" ethos as well... valiance, sacrifice, domination, fury?
What narrow ethos is described in the character writeup. It is broad and can encompass quite a bit.
Unless you use one of the various options found in 3.5 that allows you to play a non-LG paladin...
I'm not aware of these particular options so I'll take your word for it. There are quite a bit of options for the 4e Paladin, and it is not as restrictive as the previous editions as regards alignment.
I love how you just declare it "not punishment" and it's so... even though I have demonstrated how you are punished (if you consider the loss of powers due to alignment violation a punishment) if you try to play the paladin as anything but a melee defender guardian type.
I can't see what demonstration you speak of. Nothing you have pointed to has demonstrated a punishment, that I can think of. Or our definition of punishment is not the same.
Not being rewarded mechanically, is not the same a punishment. At best is the status quo. All characters get a ranged basic attack. If I have high DEX my
bonus damage is higher than somebody that selected not to invest in DEX. If I'm the player with the low DEX, I don't use my ranged basic attack because it does not reward me mechanically. Is that a punishment?
The player has made a conscious decision to select a class that has specific theme elements and mechanics tied to those elements. If he chooses to play against that theme and mechanics he's NOT AS effective as if he has played to the theme and mechanics, but he's still as effective as the average guy (everyone has RGA and MBA). If a player chooses a class that is not proficient in heavy armor and then wants to reflavor it as heavy armor, he gets no mechanical support. Is that a punishment? No that is the system doing what it has already done as part of the class balance.
That is NOT the same as, "you've violated what I believe (the DM) are the tenets of your ethos, you are no longer a Paladin".
One at best has a zero effect on the class's viability. The player can choose to start "acting" the part that is mechanically rewarded and the reward is immediate. The other is a hammer to the head, because your vision and the DM vision don't align, and your class effectiveness past that point is entirely subject to the whim of the DM.
Then how is loosing your powers because you chose to go against one of the key tenets of the class archetype any different? Your character doesn't keel over and die or get taken out of the game... he looses effectiveness for making that choice to play against archetype.
One loses effectiveness, but is still viable, the other loses all aspects of the class based on a whim. What happens to a 1e Paladin that is no longer LG, based on the subjective appraisal of the DM? How long does that "effect" last? What happens to a 4e Paladin that chooses to attack with RBAs, instead of getting into the thick of things? How long does that effect last?
If you can't see how these two things are very different then I don't know what else to explain.