This is a good move for Coinbase, i'm glad they are defending their users. They are right that it is overly broad. I don't see how IP addresses and customer support transcripts are a matter for the IRS.
IP addresses could help them identify people trying to get away with smurfing by setting up multiple accounts [see: http://www.investopedia.com/terms/s/smurf.asp], and customer support for banking is typically about reconciliation -- if coinbase has any mutable records in their databases (likely) that'd be the only place to find the original information -- if they don't get it in the first court order they won't have a super good reason to ask for it later (a judge will ask them why they think the new order is needed, and if they suspect the information supplied to be false -- if they ask for it immediately it can be used to create a more detailed picture of how certain accounts developed).
Not saying the order is justified, merely that the people asking for it want it for actual reasons.
Not saying the order is justified, merely that the people asking for it want it for actual reasons.