What is this, debate class?
No. It's a forum. Meant for discussion.
However, you assert something, then provide reasons against your own assertion. Which is not a particularly good way to make a case.
No, the argument is that these abilities are already quite common.
So... They're not "Class defining abilities" like your original post was trying to portray them as?
Thus, there's no reason AGAINST making them freely available everywhere?
There's no need to scatter items everywhere to make 110% sure everyone everywhere can use them constantly. They're also not necessary to beat the game so why trivialize them in the first place.
There's also no need to NOT give items that grant there effects. Given that they're "Already quite common" and "Not necessary to beat the game" there's no harm in scattering a bunch of items to provide their effects.
While their addition helps alleviate any pressure to run specific classes in your party (Much like how that amulet that gives the Guidance cantrip helps remove the need to have a Divine caster/Tome Warlock in the party without losing a fairly useful ability)
Another argument is that the abilities themselves are devalued if you are expected to be able to use them every single time a target is available, even if you don't have the appropriate classes.
That's a weak argument. Especially when they're "Already quite common". The fact that they're Ritual spells means they don't cost anything to use, so you literally can use them "Every single time a target is available" the only thing that the items bypasses is the need to have appropriate classes, but as you already point out they're "Quite common" spells so this is a minor thing.
Perhaps most importantly, there's multiplayer where it would be really cool that your PC could contribute something unique to the party. But these class abilities are not flavorful or unique if anyone can just use a scroll or potion to gain them.
Yeah... But they're "Already quite common" aren't they? So the likelyhood of your character being the ONLY one to bring the ability is going to be fairly low isn't it?
Like, even if they removed all the items... What are the chances that someone else has picked a class that also gains these abilities? Very high for Speak with Animals. Moderately high for Speak with Dead (Bard is a fairly popular class)
The only counter-argument that I can really think of is "they're fun to use, I like that I can use them whenever". Which is valid and fitting for some casual fun gameplay, but completely misses the points I made.
You mean, other than "Well, these abilities are already common enough that most 4 character parties will have access to them so there's no harm in having items provide them for the niche cases where someone manages to make a party that is devoid of these skills and still actually cares about the minor effects they have on the overall game"
Honestly, it feels to me that these items inclusion is more to populate loot tables with junk items (Instead of more valuable Healing Potions and scrolls of spells that are impactful) given how readily available the skills are and how little they provide.
There are many more significant cases of "Class defining features" being devalued than a couple of minor Rituals that provide a handful of extra dialogues. For example, the aforementioned Guidance amulet. Or how anyone can respec into Cleric 10 to get a Divine Intervention and then spec back into their original class. Or how water bottles devalue "Call Water" spells and abilities by not requiring spell slots or rests to replenish etc.