SEP articles are written by individual academics, who often have peculiar writing styles. I suppose the editors try to curb the most extreme of peculiarities, but all sorts of quirks inevitably leak through. Archaism and grandiosity are especially common, since a lot of philosophers spend a lot of time poring through old books.
Wikipedia articles, on the other hand, tend to have a rather bland writing style, the average of all the people who contributed to an article.
I don't understand why you think it's an improvement. If the grandiosity was just a quirk of the writing style I'd have more patience for it but the field produces an endless stream of condescension and disrespect.
To be fair, philosophers often talk to (or write about) one another in exactly the same way. They tolerate a lot of condescension and disrespect as long as it is directed towards ideas/theories/hypotheses and not people. Notice that the passage you quoted talks about "naive, untutored descriptions", not "naive, untutored people".
Philosophers are trained not to take such things personally, and to respond as rationally as possible even if they do take it personally. Since a lot of them also spend most their careers relatively isolated from the rest of the world, it's not surprising that they expect their audience to respond in the same way, especially if philosophy students are the intended audience.
No, it's not an improvement. I'm not trying to defend that writing style in any way. The above is just one explanation for why someone who doesn't actually mean to be condescending might nevertheless produce essays that sound condescending to contemporary readers.
Wikipedia articles, on the other hand, tend to have a rather bland writing style, the average of all the people who contributed to an article.