SO, SOMEONE ASKED SHORT OR LONG HAIRED TECHNO BLADE AND I RESPONDED WITH THIS
I like both but long hair is more striking compared to every other guy on the SMP.
Also, with a crown and robe, it makes Techno look a lot more like a member of the royal class. He looks more like a fantasy character than everyone else (with the exception of Ranboo and Phil (I will get to this in a minute)) and makes him look more isolated.
This is why I like that trio because the Japanese style clothing Phil wears along with Techno's royal garb and Ranboo's Tux make them all look different compared to the hoodies and t-shirts makes them isolated.
Also, due to The Wonderful Eret™ we can imagine royalty being outcasts on the SMP, making them stand out even more (Techno more so but Ranboo still wears a crown).
Since Techno and Ranboo are some of the only part mob characters people draw, they can't blend in as well so they choose to stand out. Phil can blend in but chooses to stand with his own individuality by wearing a different fashion style.
TLDR, giving the "non-humans" more fanciful/dramatic fashion expresses how different they are to the rest of the "humans" on the SMP.