Most of them sound bad because you --through no fault of your own-- have no idea how to use them, and no idea how to listen to them. Very few people are exposed to anything beyond ET and even when they are, they are rarely taught their historical use, with pieces appropriate to them, so that they can learn to understand them, and through understanding, appreciate and possibly even use them.
There's almost nothing about tuning systems that is inherently bad "because our ears", the closest to a real argument you could make is that resonant harmonics are good, but that doesn't really help us much: natural harmonics only give us a "good" tuning for one specific root note, and leaves so many notes unavailable that you'd be locked into a single natural harmonic key. Whatever pitch you come up with for any other note really is just an arbitrary (although usually at least informed by something), choice.
(Heck, starting with harmonics is itself already a choice, there is literally no reason to use that if your music is locally intervalic, where you don't get to skip up and down by intervals of an octave or more)
There's so many centuries of documented musical history, most of it not (to use a phrase that's rapidly become cliche) part of 18th century western musical canon. What you grew up with is what you're used to, and thus is what you're comfortable with, and thus is what you consider "good".
So be careful calling things you're not used to "bad": you're not used to it, so it's almost guaranteed to make you uncomfortable, and you'll be tempted to call it bad, and you should always try to catch yourself before that last step =)
There's almost nothing about tuning systems that is inherently bad "because our ears", the closest to a real argument you could make is that resonant harmonics are good, but that doesn't really help us much: natural harmonics only give us a "good" tuning for one specific root note, and leaves so many notes unavailable that you'd be locked into a single natural harmonic key. Whatever pitch you come up with for any other note really is just an arbitrary (although usually at least informed by something), choice.
(Heck, starting with harmonics is itself already a choice, there is literally no reason to use that if your music is locally intervalic, where you don't get to skip up and down by intervals of an octave or more)
There's so many centuries of documented musical history, most of it not (to use a phrase that's rapidly become cliche) part of 18th century western musical canon. What you grew up with is what you're used to, and thus is what you're comfortable with, and thus is what you consider "good".
So be careful calling things you're not used to "bad": you're not used to it, so it's almost guaranteed to make you uncomfortable, and you'll be tempted to call it bad, and you should always try to catch yourself before that last step =)