As JoBildo accurately points out, the ‘open group’ feature of Warhammer is one of those ‘no one did this before?’ types of features that just seems so obvious, especially to anyone who has played MMO’s for any length of time.
Think about it, how many times are you doing a specific kill quest, and when you get to the area you see someone else already there. Now normally, if it’s a quick quest, you won’t bother asking them to group, as the whole ask/reply/group process takes longer than it would to simply kill the 10 whatevers you are killing. If however grouping was as simple as a right-click, people would do it out of habit all the time. After the initial quest, perhaps you stick around for a few others, including some elite quests, which all of a sudden don’t look quite as painful to gather some help for.
Now if we assume that the ‘open grouping’ feature will have as big an impact on questing/RvR as it looks like it will, will this be something all current and future MMOs add in a patch? Much like instances went from being a feature to a standard, will the same be said for open groups in a year or so?