As to why it is not constructive: We don't like discussions. Ok, that's a lie, we love discussions, especially heated flamewars, after all we are programmers. However we haven't yet found a good way of moderating and curating such questions on Stack Exchange, we have an array of excellent tools at our disposal, none of which was designed with free flowing open ended discussions in mind.
This is more of a "it's not you, it's us" problem and it's a discussion we seem to be having at least once a week but the bottom line is, open ended free flowing discussions don't work on the platform, and unfortunately we have to close them.
Feel free to bring up any issues you have with Programmers on Meta, especially when it's about closed questions. Sometimes all it takes is a small edit to make the question a bit more focused for it to be re-opened...