One side benefit of OP_COUNT_ACKS is that it enables a completely different use case:

It allow users to pay for any service miners can provide as group for the common good (e.g. fee payment smoothing over many blocks). For instance, users could pay miners to jointly buy better Internet service to improve bandwidth or reduce latency between them.
 
By sending bitcoins to a script containing OP_COUNT_ACKS requiring 51% of miners approval and adding a special text tag to such outputs such as  "FOR-MINERS-TO-BUY-X", users can send bitcoins to miners and ask the majority of them to vote on the proposal, if accepted create a transaction to redeem those funds. This could help to address the so-called tragedy of the commons problem that Bitcoin may face in in long-term, by users crowdfunding mining of the following n blocks.