This is, I feel, a reasonable position. I don't even have a good answer to it.
There is a reason for that. Search your feelings, you know it's true...
This is back to wrong again. In your scenario, the "Paladins must be LG" Paladin does not actually exist in the game without rebuilding the class. Your footnote about "generically" applies here - people who want LG paladins (I assume) want a class that mechanically supports LG.
Besides Alignment Prerequisites, Restriction, and Violations Rules... what else needs to be in the package?
Smite [Opposite Single Axis Alignment]? Detect [Opposite Single Axis Alignment]? Spontaneous Channel [Single Axis Alignment] Energy (Turn/Rebuke Undead, Lay on Hands/Dish out Pain, Cure/Cause Disease, Remove/Cause Fear, etc)?
Are those things you "need" to make a "Restrictive Alignment Paladin mechanically supported by the rules"?
'Cause, you know... there have generally been two types since the beginning of the class [-]Jedi and Sith[/-] Paladin and Aunty-Paladin.
Yes, 3 is a number from 1 to 9. But I'm saying paladins are triangles and you're saying they are n-sided polygons.
I will always feel that inclusivity trumps exclusivity.
My Paladin doesn't need his own water fountain, thank you very much.
And this is why I say you don't understand my point. I am, in fact, saying that the definition of paladin as "Paladins must be LG" is not, in fact, included in the set "Paladins can be LG or any other alignment". That you are mistaken in thinking that the two are the same. This is what my examples were intended to demonstrate.
The two aren't the same.
One simply subsets into the other, one is lesser than the greater of the other. Do I really need to make a Venn diagram?
You can say (and did!) that it's better for D&D to provide Paladin(subtype=all) than to provide LG Paladin. But you can't say they are the same class.
Not saying they are. You can however very easily make one into the other by toggling a switch (DM houserules to say "Paladins MUST be LG").
Going the other way (at least in the bad old days) requires more fiddling with the class' undercarriage.
Options are a good thing. Variety is a good thing. People insisting on one true ways are a bad thing.
But, but... my One True Way (Inclusivity) is the best way.
...seems to regard NG as "True Good" and LG as "Good confined by Law" (not an uncommon view among D&D players, of course, but it seems like in Ye Olden Dayes LG was regarded as "more good" - the wheel turns and so on - don't think it'll ever turn back to LG as "more good" of course).
Go back far enough and it was "Lawful is the only Good".
I think that is where "LG is the bestest best Good" comes from.