I agree with this stance because I like to pvp and I don't want even one asshole I run into to be running bots. Simple.
If you like PvP you should get more info about PvP and how it works in MMOs : first of all, gutting API won't prevent people from cheating, exploiting and doing bad things. There already is a
bot for TESO, and it's safe to assume more will come, API or not. Second, a player "running bots" doesn't really mean anything, PvP wise. Are we talking about scripts ? Macros ? "Smart" scripts that would trigger some action (i.e. purging the enemy as soon as he got buffs on him) would turn really shitty, especially when you have GCDs to to deal with. It wouldn't give a solid advantage in PvP, since you can't really hard theorycraft any encounter and you'd spend more time dealing with your scripts than actual fighting. And about macros, with nowadays keyboards you can macro a lot of stuff, again API or not.
Third, ZOS vision would be quite okay if TESOs UI would be functional, but it's not. You have status bars at the bottom of your screen, action at the middle, enemy / ally status bars at the top of the screen. If you do serious PvP you should know it's quite tedious having too much space between UI elements, your eyes would become tired very fast and you'll see yourself having to move your head up and down to "see" the different UI elements. At least we should be able to move the frames. Let's see how it really works if you want optimal performance and eye comfort :
Red circle : vital informations zone (where critical stuff happens).
Blue square : eye comfort zone (which would vary regarding your screen's height and size).
Green thing : Head-up Display (HUD) zone, optimal eye comfort and vital UI informations).
Now regarding TESO's UI, having to raise your head / eyes each time to check whatever debuff / buff your enemy is on, is really tedious. Checking your ability bar, your status bars and your enemy's target frame requires 3 eye "moves", where in my screenshot it requires none. Keep sieges wise, you'll never see a thing, you'll spend your time jumping from one UI element to another, and ZOS bar status requires you to check the bar for seconds to see what's going on, instead of having a icon which can be seen in a fraction of second. Some people, let's call them the expert players, would like to minmax their user interface as well. They'd like a combat log, moving frames, displaying useful information to get the best of their gameplay. Saying "let's gut the API otherwise people will cheat and run bots" it like saying "let's stop waste management because the Mafia uses it to launder money". I don't know about you, but I don't want to live in a world of shit just because some people don't follow the rules.