Respectable or not modifying game textures to give yourself an advantage that other players do not have was against the spirit of the server rules, and (thanks to the Pandor controversy) is now against the letter of the rules as well.
Believe it or not, even when I 'dick around' I like to fight as best I can. I like to imagine that the skill level determines the winner of each fight even if I have a sub-optimal dueling build, not who's downloaded the best textures. Maybe that's naïve of me to assume that player skill is the most important factor in a 'competitive game'.
If you need to break the rules and cheat in order to reach your 'peak' then you deserve your ban.
Well it is against the rules now, but i know tons of players whove all used some sort of modification throughout the mod lifetime. One would almost be surprised, so its strange that such a thing is shunned. Its only recently people started to bother, maybe cause the majority of players who actually bothered to play comptetitively left now, and only those who play for "fun" are left, so now they are the majority who actually dislike the idea of people wanting to fix the unecessary eye strain that is night time, or the arrow model changes that are barely visible now.
Tons of games who still are played competitively also have similar things, WoW has tons of addons, Hearthstone has decktrackers, cs 1,6 (used to have modifiable skins) etc etc. All helpful things, but it doesnt make the player automatically better, it just aids them in order to become better. Game is lacking in areas, and players fill that up in order to be able to play at their peak.
Texture cheating couldve easily been prevented by simply fixing the areas that people obviously didnt like, like night time, arrows having low visibility etc. But it never happened so players take matters into their own hands in order to be able to enjoy the game fully.