Basically, in order to fully and completely understand the consequences of causing suffering, one must experience suffering.
God in this thought experiment, is a static "is" type being. Much like the equation (35x*15Y)/(17x*7Y) holds for several values of X and Y, "god" is the equation for all possible states and outcomes, at all temporal intervals. By plugging in the variables, you get your answer.
In this way, it is all knowing, and has a timeless quality. (this is a simplification but consider it more in this light than "crochety old deity handing down capriciously arbitrary edicts")
God's knowledge of X and Y (to carry the analogy), is not bounded by some notion of "But that's EXTREME X!!" it is merely "X" in terms of its intrinsic nature. This is how "sin" is treated. When viewed in this capacity, it becomes necessary for humans to experience "The full potential range of X", in order to have the same intrinsic understanding of the nature of X. This means human experience must include the "wantonly base suffering" seen.
Failure to have it included, is god swooping in and going "There, there humans-- Daddy god will make it all better; you dont have to experience X above this arbitrary and capriciously defined value! There-- there"
Rather, God is trying to inform you about the rational proportionality of X, and how X is defined. Swooping in and tampering with those results would ruin any and all gains in that respect.
Now, your argument is more in line of "a disease outbreak is not caused by sin!". However, consider more fully-- We have had the money, resources, and skill to create a cure for Ebola for many years now. Is it a sin that we have simply just not done it, because the number of people impacted has not been a strong motivator to invest those resources or bring those skills to task?
Selfishness of this nature, is just another manifestation of "x". It is "sin". The existence of the disease highlights and demonstrates this sin existing. Thus, the disease is necessary to shed light on the sin, and allow humans to comprehend the sin nature.
The argument thus-- that god should not make things like ebola, is again "I want to never have to contend with my sin nature." which is Affluenza Affected Idiocy. Helicopter Daddy swooped in, and made sure that nothing bad ever happened to demonstrate how shit a person you actually are.
Or perhaps, closer to home-- We KNOW how to combat the covid-19 pandemic, but we consistently choose not to do those things, and instead have directly caused the horrible and painful deaths of over 200,000 people in the US alone because of it. Those that have caught it and survived, have a certain proportionality chance of experiencing life-long debilitation from the ordeal. And why? Because we are selfish, and do not want to do what needs to be done, to prevent that harm and suffering.--- Sin.
The existence of the pandemic, is necessary to drive home the importance of eschewing selfishness. Without it, you never have consequences for the selfishness; God has swooped in, and cleaned it all up for you.