Roll20 definitely isn't "where it's at" if you're looking for content, support for various game systems, etc. (I think FantasyGrounds is way above them there). However, the UI and ease of use (and ability to use on a variety of operating systems) has made Roll20 the only game in town for my groups (quite literally).
If I have pieced together the Roll20 issue about content from other threads (mostly regarding PF2) it's that this is 100% on Roll20 and their staff to program for that service. I don't think it's even an option that the designers can make.