I think the most awesome bad idea to come out of The Last Jedi had to be Admiral Holdo’s lightspeed ram of Supreme Leader Snoke’s corpse’s flagship. It was absolutely beautiful onscreen, and something I have always, always wanted to see.
So why was it a terrible idea?
For two reasons: firstly, she comes up with it completely off-the-cuff, which suggests that she (and presumably a whole lot of people) knew exactly what that would do.
Therefore, and secondly, a weapon that devastating, whereby a comparatively small ship devastates a superduperdreadnaught, would have to be put into practice. And if a kamikaze is that effective, it will be used. (Think I’m wrong? I’ll remind you that guided missiles became a reality less than a decade after Japan flew kamikazes into US ships, and were in the planning stages even then). So hyperspace transition missiles would definitely be a thing, especially since we know that hyperdrives can be made small enough to effectively propel fighter craft.
What awesome bad ideas have you seen, and why were they bad? More importantly, could anything have been done to make them good?