While there may be a bit of truth to what you're saying, it seems like you are making a sweeping generalization that isn't necessarily true of everyone.
This is a pretty large site, with a large community and lots of different viewpoints and philosophies. You seem to be making an uncited reference to one or more example questions where you found that it received too few upvotes or too many downvotes as some kind of an authoritative source supporting the thesis that everyone on SU is too harsh.
That's like going to a gas station in New York, getting ripped off by the cashier, then concluding that everyone who works a retail job in all of North America is trying to scam you.
The problem with this meta post is that it is not constructive. You aren't telling us what we, as a community, can do to solve this problem. You seem to be making a complaint. Unfortunately, a complaint that pertains to unmentioned, unquantifiable numbers of other people is not actionable. There may be 1, 2, or 1000 people on Super User who behave exactly as you describe, but unless we can (1) identify them; (2) reach them with a message; and (3) send "the right" message to make them either change their behavior or leave, we aren't going to get anything accomplished.
Part of it is just the nature of the beast. The way the topicality rules of Super User are worded, this site attracts a lot of actually bad questions. People read the site FAQ and jump to the conclusion that this is a help forum for computer problems. It's not.
Let me re-iterate a point that I've made in many other meta posts: the purpose of this site is not to help individuals asking questions. The person asking a question is no more or less important than the ten-thousand other people who are too shy (or don't feel confident enough in their English) to ask a question. If the querant is unable to form a question in a way that could possibly be useful to more than just themselves, it is entirely reasonable to expect that their question's vote status will be somewhere in the +3 to -3 range, and probably remain that way.
If you look at the questions with lots of upvotes, they tend to be widely applicable and impart knowledge or knowhow to large numbers of users. Querants who are unwilling to ask a question that expands the scope just a little, from the immediate "tech support" problem they're having, into a question that asks, give me a piece of knowledge, should be prepared to have their question's vote status set accordingly, and possibly closed if it's egregiously bad (poorly worded, hard to understand, rant-filled, etc.)
I don't think we're being too harsh when we're not upvoting, or actively downvoting, bad questions. The site has quality standards for a reason. If, however, you spot a question that you feel is actually of good quality, and is being unfairly downvoted for some minor reason, feel free to flag it for a moderator, and let them know. Better yet, edit the question to improve it, so that those visiting the question later will be inclined to upvote it.