This is just the same principle as private organization boards of directors delegating the minutia of running the organization to the executives and their teams. If you think it would be madness for hiring decisions on individual contributors to be made by board votes, then you should support the delegation of rule-making authority to executive agencies.
Yes, it means that changing the executive might change the rules. Congress remains free to overrule the agencies by passing further legislation, if they so desire. And voters remain free to replace the executive the next time around, if they want to see different rules. These are all features, not bugs.
There is certainly value in stability and predictability, but there is even more value in having an executive branch of government that is empowered to make decisions quickly and a short feedback loop between the public and the government.
Note that there are only either 538 or 100 voters, depending on which position in the executive branch.
The ballot is a lie. You're actually voting for an elector, not the President.
In practice, the general voters typically see the electors vote the way the populace in their area voted, but that's not always the case.
When is that not the case?
I believe it would be a violation of current electoral law for electors to fail to cast votes as apportioned by the results of their state's general election.
In my view, being detached from the outcome of the general election in a state isn't the problem with the electoral college currently (though maybe it was in the past).
Rather, the problem is that the all-or-nothing apportionment of electoral college votes within most states often creates outcomes that wildly diverge from the national popular vote. But I think the idea of splitting up the general election vote tallying by state is a good one, because I think running one giant national vote would be more of a contentious logistical nightmare than it already is.
But if it were up to me, all states would apportion their electoral votes proportionally, and each state would get a lot more votes. That is, say California is allotted 10,000 "electors" and 57.25% of their votes go to one candiate, 39.67% goes to another, and 3.08% to a third, then the electoral college votes would be 5,725, 3,967, and 308, respectively. This would reach outcomes extremely close to a national popular vote, while still using the electoral college in a way that is no less ceremonial than it is today.
Also, Maine and Nebraska don't always give all the electoral votes to the same candidate. I'm not sure the process in those states, though.
I don't really have much of an opinion on how the election could be better, but there are some interesting ideas.