Q:

Suggested Privilege: Inviting new users to chat

Superpings allow moderators to ping any user on the site from the chatroom, even if they haven't been in the chat in the recent past. If the superpinged user doesn't have a chat account because he lacks the required 20 reputation it will be created. This allows moderators to invite new user to the chatroom, typically to discuss their question when doing so in the comments would be unfeasible.
My suggestion is that the "invite to chat" part of this ability could also be added as a new privilege level with the restriction that only "new users" can be pinged this way. The rep required for the privilege and the limit for when superpings stop should be clarified if the basic idea of this suggestion has merit.
Arguments for:

helps people find their way to chat when they otherwise might not
chat allows a more nuanced and friendlier interaction with new users
real-time conversation is more appriopriate to identify and improve a new user's question
promotes working with new users when their post has problems but has a valuable core question hidden within
works particularly well for site's where questions are non-technical and can have a high personal impact (Workplace, Parenting, religious sites, ...)

Arguments against:

may see very little use
moderators can be pinged from chat to superping a new user (but they aren't always around)
possibility for abuse? (mitigated by a high reputation requirement?)
promotes chat at the cost of taking the focus off Q&A ("Participation in SO really revolves around questions, not chat")
may lead to off-topic or bad questions being answered in chat, bypassing the Q&A framework and site guidelines

I believe the potential benefits to a site's community outweigh the cons I've identified, but I may be missing something. The biggest question is probably if the use and promotion of chat goes against SE's goals or not. I'm of the opinion that chat can be a valuable addition and this would allow for a softer welcome to users that might otherwise be scared away by the abrupt nature of comments and close votes.

Edit: This question originally suggested the full superping ability be unlocked as a privilege. As pointed out by Monica, the intended goal can be accomplished without the actual "ping" by instead giving users access (if they don't already) and simply linking to chat. This has the added benefit of not forcing users into the chatroom if they don't want to (clicking the superping notification will open chat).

A:

When a promising new user is having trouble making his first post and the community wants to help, we should make it easier for them to do so.  I've seen chat work really well for this, and discussion in comments is not a pattern we want to set with a newcomer's very first participation on the site.  But new users can't use chat without moderator intervention, which is a real hassle.
A long time ago in a context far, far away (ok, 2013), I suggested that "grant chat privs to low-rep users" be a new privilege.  It was well-received then and the team looked into implementing it but ran into problems.  
It's been a few years and I think it might be more tractable now because of other improvements to the SE platform.  There is now a mod-only feature to copy comments to chat, and that code implements most of the pieces we need here.  We can reuse the following from there:

Create the chat account if it does not already exist
Grant the chat user write privileges to the site's main chat room (instead of the discussion room that the existing code creates)
Add a comment inviting the user to join the chat (change the comment text from the "discussion has been moved to chat" message that the existing code posts)

We'll need to give the user with the privilege a way to kick this off (an analogue of the mod-menu option).  Suggestion: on a post from a low-rep user (only), users with this privilege should see one more option, "invite to chat".  It could go next to "add comment".  Clicking that would create the account if needed, grant the privilege, and leave the comment.  (As a stretch goal, if somebody else has already done this the link is inactive.)
A few years ago there was some minor objection that this wouldn't be needed often and we already have the "hey, take it to chat" prompt when a discussion in comments goes on too long.  But that doesn't help when several users are involved.  I've seen this pattern a lot on Worldbuilding and The Workplace: several people try to help a new user improve his first question, the user answers in comments, and, boom, 20-comment thread where nobody got that prompt.  (I think it also doesn't grant chat privs, though I might be wrong about that.)

