I have a feeling you dont have much experience on working on other peoples code. You have just bundled all kinds of issues into a bucket of "buggy piece of poorly written code". Some of these are outright security vulnerabilities and some make you wonder how was the bug not found so far. Sometimes fixing these issues require a heavy rewrite which cannot be justified as a bug-fix. And how do you justify playing with your customers data by "slapdash jquery-and-duct-tape" techniques.