I actually like a lot of things about Bozja, but think there are just some flaws that need to be addressed. Also, great idea for a thread! I think it's important we give feedback as to what we're hoping for.
1) I did a whole post wondering why we're doing Crystal Tower for the "Change of Arms" quest when we already do Crystal Tower every day with alliance roulette. I think one of the biggest problems is the low drop rate of memories, upgrade items, etc in Bozja. We need to make castrum appeal to people who have already done it. So, for example you could make each boss in castrum drop a loathsome memory, up the loathsome memory drop rate from CE's and do away with the Crystal Tower part (or make it a low chance). I'm not saying I don't content outside of bozja to not drop things you need for the relic; I'm happy with doing the HW/Stormblood raids for the next step b/c those aren't done as much. We need to keep old content relevant for new players joining FFXIV. But wow, Castrum has become a bottleneck for new players; you have to make it appeal to players that have already done it.

2) When you reach max rank in a Bozja zone [for example the current zone, max rank is 15], increase the coins you get from CE's and skirmishes--even if it's just one.

3) The upgrade items (e.g. Bozjan Secrets (Headgear), etc.) are a bit extreme at 999 and 500. Drop them just a little. 800 and 400 would be more reasonable. They should be hard to get/a grind but not demoralizing (though if at max rank, coins from CE and skirmishes were increased maybe 999 and 500 wouldn't be the worst).

Thank you for your time!