Is there a way for new CiviCRM StackExchange users to be able to comment right away instead of waiting for 50pts?
If you are already active on another Stack and have achieved 200 reputation points there, you will receive a 100-point association bonus upon joining CiviCRM.SE. Thus, you effectively start with a rep of 101, enough to leave comments and have access to the other basic StackExchange functionality like voting, flagging, and posting links. It is assumed that you have enough experience at that point to understand what the comment system is for and how to use it responsibly.
Otherwise, no, this is a mechanism in place throughout all of StackExchange (except MSE). See Why do I need 50 reputation to comment? What can I do instead? for the official FAQ on this point, and How do comments work? for the complete overview of the comment system.
StackExchange is all about good questions and good answers; comments are ephemeral.
Comments are second class citizens on the Stack Exchange network, not designed to hold information for all eternity. They may get cleaned up at any time. Generally, truly important information should be incorporated into an answer of its own anyway.
On top of this, bad comments are more difficult to moderate than questions and answers, because they require direct intervention from a moderator. Compounding this is that new users are more likely to leave bad comments (spam, discussion, "me too," and so on).
The barrier of 50 points is not a terribly high standard for a privilege by SE standards: ten question upvotes or five answer upvotes, or 25 revisions. On a full site, you need 1000 just to be able to see upvote/downvote counts.