Do you know what my favourite thing about deckstats is? It's when Morganator starts a post asking if we know what their favourite thing about deckstats is.
Spoiler alert: it's the stats.
Never change Morganator, you glorious statistician you (I don't mean that sarcastically, it genuinely makes me chuckle every time).
In terms of removal, your numbers all seem spot on for decks that are looking to be more towards the optimised, competitive end of the spectrum.
Of course, not everyone builds a deck with that end goal in mind, so numbers can vary greatly. Ultimately it will always depend on what your deck wants to do.
Morganators numbers seem like a pretty sweet place to start for someone looking to build a decent deck.
But every so often some idiot tries to build a deck with just birds and ends up running exactly
wing shards.
Spoiler alert 2: I'm the aforementioned idiot. Also,
wing shards is legitimately sweet even without the cool owl.
Then my Yahenni deck that wants to kill all the things all the time runs upwards of 25. And only one can get rid of artifacts or enchantments. Such is the joy of mono black.
But yeah, I think it really comes down to the each deck specifically. 15ish split across creature and "other", slightly favouring creature is a good starting point for a deck that wants to be good at disrupting opponents. But any number is fine if that's what you want.