Individually, the new abilities for the memories may not look as strong compared to old ones, but you should note that some cards can provide bonus to the whole party rather than just self.
For instance, the rainbow crit one provides 5% crit dmg to all party members, which you can equip multiples per party, but of course getting them would be the difficult part.
The gold rarity crit (i think it was heliotrope'd memory) provides 3% crit dmg and should be easier to get.
As for the the attribute based party member buffs, it may appear difficult to use since your typical party setup may just involve girls of multiple attributes. However, if you attempt to use them the same way as regular abilities to strengthen a single girl (Like RR) then it would yield excellent results.
Since the attribute ones with 5% skill dmg and boss dmg are only gold rarity, you may easily stack them up just to buff up RR for example and suddenly she just got a +20-25% dmg buff (20% if she's already using +weakness dmg one for herself)