Because as it stands, no film has ever been made completely in IMAX. This is as close as it gets. The scenes that aren't filmed in IMAX, are usually shot on 35mm or some digital camera. Filming those scenes in 65mm will bring you a lot closer to the fidelity of IMAX. The jump in image quality won't be as large, and the depth of field will be much closer between the formats as well, whereas the difference between 35mm and even 65mm, let alone IMAX, is absolutely massive.
There's also the bragging point of being the most high-res film ever made :). Tons of films have mixed 35mm with IMAX, but none have done it with 65mm.
It hasn't been shot on Alexa 65. It's shot on Alexa XT...
If you're so invested in having digital be accepted, why shoot down film? They're creative tools that do different things well. If you don't like it, fine! But for many of us film still represents something different and hopefully it will never die.
I don't know where they found those numbers but the body is 6 lbs. It will usually end up slightly lighter than an Alexa mini once you add rods and battery plates to it.
Weighs nearly exactly as much as an ursa mini pro...
Is raw really that important? 99% of the shoots I'm on, shoot ProRes and the ones that do shoot raw, do it because they're using red. The original Alexa didn't shoot raw and it did pretty alright for itself.
There's a video on YouTube that compares Amira @ internal UHD upscaling with Red Dragon 6k and the difference is negligible at best. Even if the difference was bigger, most consumers don't sit Cloe enough to their screens to fully appreciate 1080p, let alone UHD!