Put off by Pickups
In many games, enemies drop money, items, or other resources. Sometimes this is figurative - you just receive those resources when you defeat the enemy - but other times it’s literal, with the resources appearing as pickups where the enemy was defeated and not being received until you go collect them.
I think the pickup approach is almost always a bad idea.
To illustrate why, I’ll start with an example of a game that does it well: Super Stardust HD.. An Asteroids-like shooter where you navigate a crowded level avoiding and destroying hazards, safely collecting the pickups dropped by enemies and rocks is part of the always-be-moving-always-be-shooting challenge. But it’s more interesting than that, since some pickups change over time and you might want to let them change before you nab them - plus, boosting through a large number of point pickups in one go rewards a significant bonus, so there’s a risk/reward trade-off. The point is - collecting the pickups is just as interesting a part of the gameplay as destroying the enemies in the first place. It challenges the same skills and presents similar interesting decisions.
This isn’t the case in most games. Usually, collecting the pickups isn’t interesting at all; it’s just another thing you have to do. Defeating the enemy is usually the interesting and challenging part, and going over to collect the pickup is usually an extra rote step you are obligated to take for no clear reason and with no interesting challenge or decision involved.
As a player, your instinct might be to minimize the time the interesting action is interrupted by uninteresting action and just collect all the pickups at once after defeating all the enemies. But obnoxiously often, games punish or prevent this - pickups fade away after a few seconds, or the action continually leads you away from where pickups have already dropped, or defeating the last enemy immediately ejects you from the area without letting you collect anything. So your attempt to maximize the enjoyability of the game is punished by the game robbing you of the rewards you’ve already earned in combat.
It is fun seeing the resources drop, but there’s no reason to force the player to collect them. (Oddly, Hyrule Warriors recognizes this with rupees which shower colorfully out of enemies and pots before being collected automatically but still obliges the player to pick up dropped materials and weapons which are much easier to miss and much more valuable.) Some games - I think Kingdom Hearts did this, I’m not sure if the sequels all do - include optional upgrades that increase your pickup collection radius, allowing you to mostly forget about the tedious collection and just enjoy the game as it should have been all along.