Just do it. Seriously. I no longer have a job where I have to put up with this bullshit, but I did at previous jobs, and eventually I just started doing the tasks that needed to be done to make code nicer. I'd spend roughly half my time doing necessary tackling of technical debt. I even got thanked in the end, when new features post-refactor ended up not being the shitshow that they always had been prior. People don't know what they want until they have it. Lead them to the promised land.