From a purely pragmatic point of view, this is probably a bad idea. My take is that new architectures/ABIs get a certain "budget" for doing "weird" things. Ever

From a purely pragmatic point of view, this is probably a bad idea. My take is that new architectures/ABIs get a certain "budget" for doing "weird" things. Every choice you take that isn't the same as existing mainstream architectures (and notably everything that's not the same as x86) is extra work to get the software ecosystem to support your new architecture. So you really want to pick and choose what you're spending your weirdness budget on, because if you blow your budget then the result is that too much software will fail to support your new architecture in a timely way. Another example of this is that there's an argument that an ascending stack would be better than a descending stack -- but almost everybody (HPPA being the only exception I can think of offhand) has a descending stack, so you have to really really believe in the merits of ascending stacks to pick that over "just do what the rest of the world does".