Shortcomings should be addressed by forking bitcoin into yet another altcoin and demonstrate the proposed improvement over there. We now have 700+ alternative "altcoins" in circulation, most of them demonstrating pretty much nothing at all. Real breakthroughs are once in a blue moon, while all kinds of useless criticisms are plentiful. In that sense, we do not want to have a "legitimate discussion" but to observe legitimate altcoins embodying improvements, while they are performing in the real world.