Management acts this way because they have no way of evaluating the effects of maintaining code quality. Only developers with significant experience are able to evaluate the long-term impact of each technical decision (and even we are still not very good at that).
<rant target="not you">
And why should management be able to evaluate technical decisions and code quality in the first place? That's our job! The problem is that we have given management the false choice of lower quality + faster shipping vs. higher quality + slower shipping, when in fact we should not have given them any say in the matter. And before we hit me with the but we have to be first to the market and fix it later line, I need to point out that companies don't die because they were not first to the market, they die because their operations and development became so slow and costly that they could not compete anymore.
What we should do as developers is to stop talking about code quality to our managers! When we are asked for an estimate, we give them as accurate estimate as possible with the code quality that we feel is sufficient for long-term maintainability of the system. And we don't negotiate on quality anymore, and especially we don't negotiate on estimates! Only functionality (MVP and all that). Then we don't need to ask for refactoring time, rewrite time, code polish time, stabilization time on our systems (that we hardly ever get anyway), because it is all in there in the original estimate.
Management expects stable productivity, they base their estimates of operational costs and investment costs on the number of people working on the system, not on the age of the codebase (why should an old codebase cost more to work with? they ask). If we give them false hope on the productivity of the team by producing crap fast in the beginning, the whole business case may collapse when we produce the same crap slower and slower and slower later. Management is in no position to evaluate the effects of bad code on the business case, because they don't understand that. We do. The only thing we can do as developers, is to remove the option of low quality code altogether.
And we say that it is so slow to create quality code? And estimation is hard?
We learn it. We can write high quality code as fast as the usual junk we see in most systems. We keep track on our estimates and evaluate how well we did, and improve. But it takes effort. All I can say is that it is our responsibility.
</rant>
On a positive note, the solution to this on a personal level is to find a place to work where technical excellence is built in the development culture (and there are such places), and cultivate that culture especially with the new hires (mentoring, pairing, etc.).