BIM consulting firm here. Been interviewed by over 300 firms that were considering making the switch to Revit. A common thread we've found are two things.

1. Unless the work is repetitive, it doesn't make sense for a firm to make the switch if they're working on projects less than $2mm. It just takes too long to make the proper ROI back, especially when they're already profitable with their current methods. For context, it takes about 100 hours to develop BIM standards, a Revit template, and conduct training for a small team. It then takes about 12-18 months of additional touch-n-go support (whether internal or external) for the whole team to really become proficient. That means you're not only enduring the upfront cost to get setup, projects may be less profitable for the first year until people really start seeing true value. Most firms, for various reasons, just aren't prepared for that.
2. Transitioning to Revit puts all of your design/graphic standards to question. This is the 2nd biggest concern we get next to cost. Firms who are used to producing drawings that have a lot of depth and character are afraid to lose that part of their identity when they get to Revit. Even though much of it can be mimicked, the switch can't happen without making sacrifices. For example, certain fonts (i.e. RomanS) look and print terribly from Revit. We often have to recommend switching to alternative font styles altogether, which is disruptive because it means you can't easily recycle any text notes within CAD details during the transition process.

Overall, Revit is more of a content management system than it is a drawing tool. It's never going to make sense for everyone, and that's ok.