They created the electoral college system mostly to appease the South. They had smaller populations than the Northern states (well actually the North and South had about the same number of people; only problem is 1/3 of the Southern population was enslaved) and wanted more political power than they deserved, partly over fears that under a popular vote system, the Northerners would overrule them and eventually abolish slavery. With the electoral college, slaves in the South couldn’t vote, but they counted towards the number of electors. So in effect, this all meant that a vote from a Southern white had more weight than a vote from a Northerner. We can see the effects of this by noticing how 4 of the first 5 presidents of the US just so happened to be slave owners from the South, and how most presidents before Abraham Lincoln were pro-slavery.

Also, the system they came up with in 1789 was horrible. They had to completely overhaul it just 15 years later, following the dumpster fire that was the 1800 election, passing the 12th Amendment to the US Constitution in 1804.