Terminology does two things:
A) It terrifies or confuses those who don't know that particular piece of jargon, making the subject seem more difficult than it really is.
B) It provides a very useful shorthand for discussing the subject with other experts in the same field.
It's definitely important to be able to explain technical terms in simple language. Sometimes this is difficult, because some technical terms have prerequisite knowledge, so you end up explaining the jargon by using jargon that you have to define by other jargon to eventually get to the english. But this is also the strength of inspeak - it's not just shorthand for one concept, but it can be shorthand for a concept built upon other concepts, which might in-turn be built upon more concepts. So in a single word you can, among people who both already understand the terminology, refer to a complex subject. Jargon becomes the "simple english" for what would otherwise require lengthy discussion to get two experts to be on the same page with each other.
It's a conversation compression algorithm.
A type of substitution: compress [complex subject requiring ten minutes of conversation] into [single phrase]. But this only works if both members of the discussion already know that [single phrase] expands to [complex subject].
It's very useful. TV Tropes is the same type of system. Video game genres (FPS, MMORPG, Rogue-like) and book genres (SciFi, Biography) are also terms that describe a takes-ten-minutes-to-explain subject in a single word or phrase.
In my family, we often hold discussions with loads of shorthand gained from shared knowledge or shared experiences, sometimes having conversations so complex (that all of us understand perfectly) and at such a fast pace, that on several occasions outsiders have thought we were speaking a different language (and in a manner of speaking, we were!).
Though that might be partially because we have a funky family accent though when we start talking fast.
When answering beginner questions in the For Beginner subforum, I try to resist using too many technical terms, but I also make an attempt to introduce a few terms when explaining a concept. "Blah blah (also known as Foo) might be useful here to you...", to teach the inspeak so their googling, and communication with other developers, provides more fruitful results.
Using too many technical terms can demotivate people by making them think they are "too stupid" to learn such a "complex" subject - not realizing that memorizing shorthand has nothing to do with intelligence, and instead is just accumulated knowledge.
I don't find Stack Overflow more technically knowledgeable or more experienced than many of the people I interact with here on GameDev. I do find Stack Overflow to be a bit more technical-nazi-esqe, and feel that the site's format unintentionally promotes a dictionary knowledge of jargon and 'first post'-ing rather than a community of explanation and encouragement. They tend to write like wikipedia articles, and I feel they aren't always writing to help the asker (and later readers) understand, they are writing so their peers will upvote them. And to stand out from the other answerers, they have to make their answer longer and better formatted, and then copy+paste details from other answers so their answer is the most 'complete'. This works great for the end result (easily googable answers to specific questions), but badly for the community built around producing that result.
Okay, so I unintentionally do the same thing (longer and better formatted posts) here on GameDev.net also... but my primary motivation in responding is helping the individual (I hope), and the length of my posts mostly comes from a lack of skill in being succinct rather than trying to stand out.
I just feel odd in Stack Overflow, like the extrinsic motivators are forcing me to conform to a less-human and more-sanitized and 'dressed-up' but ultimately fake attitude. I feel like the design of Stack Overflow unintentionally encourages the users to treat each other as part of a system rather than part of a community.
It's that the community of Stack Overflow competes with each other for who can come up with the 'best' answer, rather than cooperate with each other to share common knowledge or discuss and explain a topic.
On GameDev.net (and in other forum-like systems), we often build off of each others' posts. In Stack Overflow, they sometimes steal each other's post content and reword it to expand their own answers to be voted above each other. The site's design encourages this kind of behavior; it produces results, but not community (a little bit of community exists there despite the system, but isn't strengthened by the system). Leastwise, that's my opinion, analysis, and criticism of Stack Overflow.
Other sites within the Stack Exchange network seem to do alot better community-wise, especially when the site's topic is more subjective, and the site size is smaller.