There's a great quote from Lou Montulli:
> I laughed heartily as I got questions from one of my former employees about FTP code the he was rewriting. It had taken 3 years of tuning to get code that could read the 60 different types of FTP servers, those 5000 lines of code may have looked ugly, but at least they worked.
Those frameworks and existing components most likely have a lot of hard-won experience embedded in them, and I would be uncomfortable hiring someone who did not appear to understand or appreciate that.
See also: Chesterton's fence.