I'm actually almost as disappointed by what Ritual Caster gains as by what it loses.
While the Quick Ritual feature may compensate power-wise for the inability to learn new rituals, it really doesn't fit the sort of character I'd want to create with this feat: someone who lacks a spellcasting adventurer's capacity for time-sensitive magic but who can manage a few spells if given time to sit down with a book or pray/meditate. I could imagine this sort of character being common in a lot of settings, but it's not supported rules-wise if learning rituals comes as a package deal with the ability to cast them quickly.
I wonder if the developers' reasoning here is the same as with Healer. Make a feat that gives characters a new ability attractive to characters that already have that ability.
As in that case, I think this is a mistake here. Characters learning new ritual magic and characters looking to exhance the ritual portion of their existing magic would both be better served by dedicated feats than by a single feat trying to do two things at once.
That might be a bit much for a single feat, but I'd at least make it repeatable to choose multiple classes.
Some shorter thoughs on other feats:
Keen Mind/Observant: The previous iterations of these feats were niche but they definitely had appeal for some players. The new versions actually seem more DM dependent, in that they codify moving an action to a bonus action, while leaving what that action can actually accomplish undefined.
Lightly Armored: Glad to see this improved. The 2014 armor proficiency feats seemed like a perfect example of the sort of feat chain the developers were trying to move away from. And with the changes to dwarves, it's nice to have an option to add armor proficiencies at level one.
Heavily Armored: But then this stays exactly the same, despite a +1 ASI becoming a default part of feats, rather than a balancing mechanism for weaker ones.
Resilient: I feel like this should be repeatable for different saves.
Spell Sniper/Sharpshooter: If the developers want feats to support ranged attacks in melee combat, they should design feats around that focus, not tack an ability onto feats focused on long range combat.
Weapon Training: The improvement from four weapon types to all martial weapons is welcome, though it does create an amusing scenario where a wizard who takes it can proficiently use any martial weapon but is still limited to a subset of simple ones.