I've already noticed when answering that if you write blocks of texts such as this one or this one or really any block of text of 3-4+ lines: the text is not justified. This is not a matter of life and death but it annoys me more than I can explain. Couldn't a text formatting feature, much like Microsoft Word one (align right/align left/center/justify), be implemented?
No. The posts intentionally don't allow complex styling (yes, bold and italics are allowed, but they are for highlighting the text).
Let's assume for a while the website allows justifying the text. What would be the result? Well, I have seen forums allowing you to align text. It causes the website to not look consistently - some text is justified, and some is not.
You may think that the solution is to justify everything. Let's even assume the post you linked to would be justified. Web browsers have ugly rendering of justification. In this examples, lines 1, 2, and 5 have 6 pixels spaces. Lines 3 and 4 have 8 pixels spaces. I like having consistent spaces. This is a noticeable difference, and there are worse examples than that. Browsers try as much as they can, but there are ugly differences (compare "changes is" on second line, and "6 so" on third line).
I would advise against justification as is. However, CSS3 introduces
hyphens property (I assume the support for it could be detected, and the standard left aligned indentation could be used if it's not supported), which makes justification actually more usable.
One hyphen, and the text looks better. The browsers sadly don't support LaTeX text hyphenation algorithms, but it already quite looks well. I wouldn't have an issue if Stack Exchange would support justification, but only if the browsers support CSS3 hyphenation. Of course, it's not that it's a huge improvement from left aligned text, but at least it improves, unlike standard justification.