There are a zillion ways to make a product insecure, and manufacturers manage to stumble on a lot of those ways again and again. No one is paying attention because no one has to. Computer security products, like software in general, have a very odd product quality model. It's unlike an automobile, a skyscraper, or a box of fried chicken. There goes another one.
Software is different.
It is sold without any claims whatsoever. Your accounts receivable database can crash, taking your company down with it, and you have no claim against the software company. Your word processor can accidentally corrupt your files and you have no recourse. Microsoft fielded Hotmail with a bug that allowed anyone to read the accounts of 40 or so million subscribers, password or no password, and never bothered to apologize. Software manufacturers don't have to produce a quality product because there is no liability if they don't.