The point of redirecting to HTTPS is so someone cannot MITM your traffic. HSTS ensures there's only one chance for that to happen as your browser will remember

The point of redirecting to HTTPS is so someone cannot MITM your traffic. HSTS ensures there's only one chance for that to happen as your browser will remember the HTTPS redirect. This kind of redirect does not provide the same benefit. An attacker could just tamper with the JS to remove that code, and this could happen on any visit, not just the first.