The states negotiated terms before they agreed to join. Not having a popular vote is part of the reason why we have a federal system in the first place. People can argue pros and cons, but it's fairly meaningless since we're already in an established deal, and it's very unlikely that the many states will agree to undo that deal.

Electing a president via popular vote would give populous states disproportionate influence over the country compared to other states. That is important because the president could do obnoxious things against the best interest of any particular state, especially ones with less influence. The stuff happening to your home state is way more relevant to your life than your political party or special interests.