The time limits are because you are new (basically spam prevention).
What you are experiencing is the difference between posts (questions and answers) and comments not some kind of "replies to a thread."
Comments are meant to be short and simple (not an answer). There are no need for paragraphs, nor a full blown editor in the input box. You rarely need a larger input box for a comment (comments are limited to 600 characters anyway), but it can be resized. Just drag the bottom right corner.
Questions and answers (the real content of the site) is where everything happens. It is here you get full formatting, images, pretty code, etc. Because SE is a Q&A site, not a forum, the comments are treated much differently then questions or answers.
Nope SE will never change this core model to incorporate more "forum like" responses or features. Why? SE is not a forum. The site tour does a pretty good job of showing what SE is and how it works.
As an example: with an ideal question, there is no "discussion" there are no replies, or digging through pages of threads to find the answer. Simply a question, and answer(s) to that question. PS Anything posted in the answer section that does not attempt to answer the question will be deleted.
blenderartists (a forum) is great for art feedback and discussion. BSE is not for any kind of discussion. (If you want to discuss take it to chat or off site.)
Forum = message board for open discussion
BSE = Q&A site for blender
I'd be very surprised if we have no tags that cover your blender questions. Yet if there really are none then maybe that is telling you that your question is off topic. You might want to double check that if you find no suitable tags.