There are 3 base Balance Standards: Non-Rare, Rare, and SCMM (stated before by Warlic and blues, echoed again recently by Korin himself).
The issue is that a small portion of MQ's non-holiday/non-Rare-event enemies (most enemies post-Necryptos) seem fully based on the Rare Standard (and by extension, Non-Rare NG Standard), instead of fitting between the Rare and Non-Rare Standards like the Pirates and Arthurian mechs (ranging from Easy to Hard depending on the machines; 2 of which were Rare, the rest all purchasable for either Credits or NGs).
I'll use Yokai since it is a pretty popular excuse. The enemies all featured pretty strong Nerfs that weren't seen in Non-Rare enemies and equipment until recently, and it isn't until you master the basic training on-site that those weapons are made available for the general populace. Of course, most everyone was here for the GBI threads crying for Mass-Nerfing, just because it was "an impossible" challenge that they didn't want to work to overcome. But for those who steeled themselves and completed the Training, they soon found weaponry that not only rivaled Rare equipment, but was worth the work to obtain, and weren't Rares.
Granted, this form of Shock Therapy may serve to help close the already minimal issue of power inflation, by releasing some rather strong weaponry to those who are willing to work for them. While it also proves harder to obtain than Holiday Rares, at least the content within is Non-Rare, powerful enough to take the place of some Rares, and not easily obtainable to start a new series of complaints basically stating "WAAAHHH!!! IT'S NOT FAIR THAT THOSE WEAPONS ARE POWERFUL BUT NON-RARE AND EASILY OBTAINABLE!!! NERF THEM NAO OR MAKE THE NEXT RARES STRONGER!!!"
Back to the general base of the issue, more of the enemies and their equipment should fit between the Non-Rare and Rare Balance Standards, so that while Normal fights aren't too bad, they're also not as easy as many Non-Rare-using NSCs say they are. Basically, a blend of what was done right for Lagos; a few hard enemies (what the Sniper, A.Bull, and the Navigator were considered), a few easy enemies (what the Blademaster and A.Wolf were considered), and a fair mix of enemies with varying difficulties depending on their attack order (Anchorman to Pirate Admiral to A.Ram).
As for Necryptos, while Necryptos requires a Vampire Hunter, it's not that different from the occasional mission line in DF or AQW where a specific Armor is required in order to accept/complete the mission set. The issue is that the Anti-Vampire weapons; defaults or not (except the BA of the Mogloween Editions) are still lackluster, echoing the failure of the Zargon BAM weaponry. After all, unlike the rest of AE's games, you can't equip/unequip weapons at whim during battle. The weapons themselves in MQ have to be flexible enough to warrant purchase and use for the duration of any particular mission set. If the Staff really want to encourage (make) players use V-Hunters, not only will the Non-Vampire weapons overall need varying levels of Buffing, but incentives to using them over waiting to hoard Rares. Let the base special and DPT be tempting enough to work with (somewhere between Yokai-level Non-Rare strength and Gark/Lagos Non-Rare strength), but add a bonus special that's only activated if the weapon is equipped on a V-Hunter (and whoever thought it was a great idea to make a V-Hunter themed weapon have an extra special when NOT on a V-Hunter needs a reality check).
Miracyrina could be considered a V-Hunter Challenge, if choosing to view it that way instead of as the only Boss standing in the way of completing Necryptos. See how well you do against her using only a V-Hunter and V-Hunter equipment. In fact, all of Necryptos could be considered a small Challenge, relying only on a V-Hunter and the current average to below-average V-Hunter weaponry and personal strategy to master the Planet. Rares just makes things easy, as do better off-planet weaponry. At least you're not getting penalized for equipping non-Vampire Hunter equipment on your V-Hunter.