All are good points but reward (money) is involved things get complicated. 7 days limitation is for how the blocks are created and how reward is calculated. Here "code is law", that needs adaptations (hardforks) to find optimum solutions. For example, nobody will STEEM, if it does not provide benefits (more SP, more VP, or price speculations). When someone with SP (a human being) will behave according to his traits. It is hard to find all the solutions with "code", that's why more updates are required. STEEM already had lots of upgrades (hard-fork), more are coming.