The UI could definitely be improved, but the core team has recently hired a UI designer, so hopefully this will improve in the future. If you have any other feedback that you've heard from your trainings, I'm sure the core team would love to hear about it either in their issue tracker (e.g. github.com/vector-im/riot-web/issues for Riot web), or in the Matrix rooms (#riot:matrix.org or #matrix:matrix.org).