@Zeke If we look at Episode 4 with some of the early weapons to really topple over the Nemesis/Raven "meta" at the time there were numerous complaints I recall seeing about how it was impossible to see a Jupiter Tullus drop. When it did show up it was extremely expensive and the same would have been seen for things like a Rappy Egg and a Rykross Staff.
The drop rates for this game in my experience never got "better" because unlike the Japanese side we were also given alternative grinds (either you run out and play the quests for hours and hours to mimic the Japanese version's month-long hunts on randomness to get the parts you rneeded for Atlas EX or you can take the new Collection Folder and repeat it a few times every few days to quickly get a similar but manageable grind). The global players never got to play this content for the same length the Japanese players to see how nasty the drop rates truly are which was largely part of why I was such a casual player on the Japanese side (I only ever got one thirteen-star New-Type weapon to drop for me and that ended up being Twin Machineguns which only allowed the Gunner, of all of my classes, to reach Level 80).
In a lot of ways I would be curious to see what kind of progression would actually work that doesn't result in overloading resources for older players (Warframe has this where some of the early resources gets pooled into the millions and nothing in the game ever costs that much so some equipment costs can be impossible for new players who haven't already played for months/years if the prices and costs were scaled up) or games that just get overly punishing where a drop might not exist unless players farmed that piece of content for months on end.
Personally to me in terms of rarity I would much rather go with the Dragon's Dogma Online approach of giving players an easy-to-see tier list of equipment ranging from "budget" gear for players who don't like grinding that give the absolute minimum amount of power to pass gear checks for participation, a "middle tier" gear set for players who do light grinding and don't feel extreme enough to run the high-end content to make their to the final tier but gives a noticeable edge compared to the budget tier, and then the "high tier" of equipment that requires the sort of "elitist" grinding and farming needed to get the equipment in the first place. In the case of Dragon's Dogma Online, you can use the game's auction shop of sorts (the Bazaar) to buy the resources and crafting materials to make the budget-tier weapons. To move onwards you needed to fight the higher-level enemies and clear dungeons that are limited by time so you are forced to make time on your schedule to go out of your way to find that content that showed up once every few days. The high-end equipment typically already required you had the previous tier in order to meet the minimum requirements (effectively the budget tier is trash for this content) and you play through content like the raids and more time-gated content (along the lines of Omega Masquerade and solo Sodam with their limited runs) in the hopes of getting the materials you needed to drop.
I feel that in Phantasy Star Online 2 there is simply no real incentive for anyone holding a Millionaire/Croesus weapon to look for an upgrade unless it was handed out like how Rivalate was and when we get to it eventually the Klauz/Agile weapons will be handed out too just like they were on the Japanese side. I have several friends who simply aren't invested in affixing or caring for their equipment but run the content because they can and are confident in being carried by the party and any attempt at me trying to explain to them what equipment they should be looking at for upgrades ends up resulting in them saying, "I'll just stick with what I got for free" because everything else is too overwhelming. Considering this game's difficulty doesn't reach anything quite like how Dragon's Dogma Online did it is saddening to me in a way that players simply can get complacent on what they are using and not seek improvement. But at the same time, I don't quite agree with how Dragon's Dogma Online always downgraded equipment in future content (the "high end" weapons I mentioned become nearly trash and are barely better than the "budget-friendly" weapons of the next content).
Unlike Phantasy Star Online 2, however, there was no free in-game alternative to simply power-leveling or skipping tiers without being carried or paying your way through the Weapon Lottery (a gacha shop where you get weapons that give you a power advantage up until a tier or two below where you are going to which the budget options are simply that much better). In that case, even having the previous high-end weapons would make the Weapon Lottery altogether a waste of money because everything you could pay for are effectively downgrades to what you grinded for already if you were very close to the current content.
I don't mind items being rare but I am more interested in seeing how Sega decides to handle having so many different series of weapons that are functionally the same and the difference is largely in numbers. I feel that the addition of S-Class Special Abilities (SSA's) helped individualize weapons but the problem suddenly went to prioritizing the weapons that have all the slots (Atlas EX, Agile, and Klauz weapons) simply for how easy they were to work with in comparison to the alternatives. I do not believe "higher rarity" should innately mean "more power" and would personally love for a way for even low-rarity equipment to still stand a chance especially in a game that is more about the player's skill rather than the equipment alone.