Are you not a Tiefling, if you are the spawn of a fiend, regardless of if you're a dwarf too?
Wispling = Halfling Planetouched.
Maeluth = Dwarf Planetouched.
Tiefling = Human Planetouched.
Fiend Folio, 3ed (?)
You seem to be saying that pre-4th ed., tieflings were not a "weird" race, but since 4th edition, they are? If so, that interpretation of what constitutes a "weird" race seems to be very different than how other people are using the term. And I am not sure how having horns makes tieflings any more or less "weird".
Correct.
3rd Edition. Monster Manual.
"Aside from a demeanor that many find disturbing, many tieflings are indistinguishable from humans..."
You do not think bright red skin, huge bulbous growths/horns, and an obvious tail would make someone seem 'weird' in comparison to someone that is 'indistinguishable from...' a human?
Ummm...no. A tiefling that hates devils and specializes in hunting them down and killing them is an interesting character (and makes for an interesting cleric or paladin). A dwarf that hates dwarves and specializes in hunting them down and killing them is a serial killer (and possibly an interesting villain for the party to face, but in any event, a very different character).
That wasnt the argument. It was tiefling hunting tiefling. If its Tiefling hunting Devils, then yeah sure.
However it could be as noted X race hunting devils because Y member of said race was in a cult, or is the spawn of a cult, and is planetouched as well.
You can't tell the story of Blade if Blade were just a normal human. His vampire half makes his story different...
I would agree! However why?
Because he is fundamentally 'other' than both Human (needs blood, benefits of Vampirism) and Vampire (walk in the daylight, assuming the movie was accurate to the character I dont know, I didnt read the comics).
Which gets back to is the point of tieflings to be so clearly, openly, distinctly 'other' and if so, do they stand out to the point of being 'weird' for a setting and potentially detrimental from the POV of the DM.
Again, I'm all for Tieflings, at least the pre 4e ones, but I do not see them as (outside of mechanics) doing anything really that cannot be RP by another race, UNLESS they depend on looking wildly different, aka the 4e look. They are fundamentally planetouched humans.
Essentially: If they must be so distinctly other, then yes they are 'weird'. I personally do not believe that needs to be case, but that is because I refuse to accept 4e visual representation, and the Asmodeus lore change in my head canon and so for me, Tieflings are not 'required' to play the tropes listed as arguments for their inclusion. It can be done in another race, with a different back story, unless.
1. You need the mechanics of a Tiefling.
2. You want the horns.
3. You specifically are playing within the FR setting within the regions explicitly defined within the Tiefling lore of that period.