Well, if they ban everything that works then it's no wonder that they often end up in such a mess.
I agree, but is it really that different from the all those other fantastic technologies-of-the-week that could have helped solve a lot of problems, only to never be seen again after that one episode ?

As for the spore drive - I must admit to not having seen Discovery yet so I could be wrong - I understand it is nearly instantaneous but still needs an organic driver. at this point.
So if you employ an attack fleet with it, there's no limit to the amount of surprise attacks they could do. This would make any kind of strategic defense deployment meaningless. Before any alien fleet would even be aware of what was going on and could use their instantaneous drive (they couldn't afford to not acquire that technology themselves in whatever way, legal or not, after all) to come to the rescue-- there could already be millions of deaths. So, without the option to prevent many deaths, that would only leave a revenge surprise raid by those aliens. All in all I could very well see it as the kind of technology that could completely escalate a war that would have been far more 'localized' with conventional warp technology. We wouldn't like them using it; they wouldn't like us using it, so in the end all parties agree on not pursuing the technology any further.
But again, I haven't watched the series yet, so perhaps there's some detail in the spore drive I wouldn't know about that renders the above scenario impossible...