One of the biggest issues is the lack of freedom free accounts have due to RC limitations. Removing or at least decreasing these limitations would give a much better user experience to those new to Steem and its blockchain.
Another big issue is simplicity. Things should be as simple as possible for the end user. The general population likes simplicity when using their social media outlets. I know allot don't view Steemit (STEEM) as social media but I disagree. I think the social media aspect is what attracts most users to this blockchain.