I think a great way to make things more challenging would be to remove certain rank rewards. Such as removing flight until you are Master Crafter or higher.
There could be a way around needing towns to protect builds such as being able to buy player blocks like other survival servers, which gives you an area where inside is not able to be griefed unless the player who owns the plot allows other players to edit.
I believe that it is too easy, losing items and XP should be a tier thing also, The higher the rank the less percentage of the inventory you lose. Making the ranking more crucial and effective for people who don't like to build giant structures like some of us do.
Another thing is that around spawn is insanely crowded with builds from before I even showed up, maybe removing the first 2 years of builds in that area would mean that leaving the spawn island for new players makes it easier for them to start off on the right foot and would decrease the amount of griefs that happen on a day to day basis of new players collecting resources from those buildings.
Towns that are not active and run out of money should be removed making it a free for all for players to loot and carnage making the caution for not paying taxes a high priority, keeping regular players active to farm to collect money to provide for the town. This also makes it more exciting for players who live off others resources to then loot and fight each other for the best loot in that town, making actually having armor and good weapons a luxury.
I love this server but the one big thing that is making it too easy is the card system. Although amazingly presented and made, the fact you can get 1 diamond a week, 1 diamond block a month and various armors with insanely high enchantments on them once every 6 months is making it so I haven't had to go mining or get XP in years.
Pri and the strong and beautiful staff members who I have known and shared the funniest moments in gaming have done an amazing job throughout the years, keeping the server safe and making the general mood positive, But you're right Pri its time for things to change even if its one step at a time.
Thank you for taking the time to read this, I hope that it was helpful in some way.