Also, Reddit is cool, and there's ton of quality discussions - usually under particular subreddits. For example, I love /r/KerbalSpaceProgram for a perfect combination of being large, friendly, fun, and full of people willing to teach each other some more advanced science.
To address your point: I think current downvote gate is fine and adjusting it up won't really help much. What would help (though I don't know how to achieve that) is people realizing that when saying anything controversial, you might end up getting a bunch of downvotes immediately, but the score usually settles to a reasonable value within an hour or two. It takes time, but one just has to get used to it.
TL;DR: karma comes and goes; look at it through a low-pass filter, to filter small variations.
I nearly always agree or can be convinced by the higher karma users, but the fresh users seem to be defaulting to reddit-level arguments (uneducated, immutable beliefs, hyperbole, taking things personally, no objectivity). I.e.
> just that everyone who doesn't run a mail server hasn't had to deal with this shit
"Everyone" in that sentence should not have the right to be downvoting in the first place.