Responsible disclosure is intended to be ethical, the opposite is ... well, irresponsible.
I've worked with irresponsible security disclosurists before, and even those that agree to a window only to dump another small variation after the window is up - rather than working to make sure the product is as good as it could be.
Giving end users time to patch so they are not owned is quite a ethical thing to do. The end goal is less compromised systems.
Doing this at the same time achieves the opposite effect and increases the amount of compromised systems.
It's never been "we're giving you two weeks, get it done fast because the exploit is going out then", it should be "we'll give you enough time to fix this properly, and then give the customers time to update once announced".
I personally would always release when something got done early, just because the person on the other end is usually unpredictable. However, the person on the other end shouldn't assume development of the fix didn't take the full interval.
Let people pen-test after they had a chance to update to secure the systems. Having the ability to prove a fix is not worth systems being owned prior to being able to fix them. The damage is already done at that point.
I've worked a lot of CVE reports, and about half the time, the person on the other end just wants credit, they aren't really going to hang around and try to help, and often they supply terse information (i.e. no exploit PoC to the vendor) as some form of game. I'd much rather this always be more user focused, the ultimate desire should always be to help the end user, and often users are less educated and don't have dedicated security teams.