[2021] Blade Blast triggered by Kitava's Thirst always targets the player, never a monster

This is not a bug. Triggered Skills always initially target the source of the trigger event. If that isn't a valid target for that skill, they'll look for valid targets in a short distance around that source, and retarget to one if found, otherwise they'll just target the location of the trigger source.

With Kitava's Thirst, you are the source of the trigger, because you spent the mana. Conductivity and Lightning Warp are skills that can target enemies, but cannot target you, so they lok for enemies to target, and will do so if they find any. Blade Blast is not an enemy targeted skill, it's location targeted, so it doesn't look for enemies because it couldn't target them anyway, and targets your location.

Being able to target enemies has the effect that hovering over an enemy and pressing the button will centre the effect on that monster's location, rather than the location the mouse is pointing (whcih are generally different, because you often hover the cursor over parts of the monster other than it's feet, so the "location" pointed at if ignoring the monster would be behind it. This also means they namelock while you hold down the button provided a monster was highlighted when you pressed it (and that monster is still alive).

Skills (other than self-targeted ones) are usually able to target enemies by default, and only don't do that for cases where the above behaviour is undesirable. For something like a curse, it's intuitive and expected that if a specific enemy is highlighted when casting, the curse is cast centered on that enemy, rather than behind them.

Blade Blast doesn't target enemies because you need to be able to accurately target locations near blades that are on the ground, and don't want monsters walking in front of the cursor to interfere with that. Storm Call is a similar skill that benefits from precise location targeting and thus doesn't target enemies (although I believe it originally did and was changed). One other common reason for skills targeting specifically locations and not enemies is moving the player.