In KHI, it is said that the Keyblade chooses its master. We see this in action when the Kingdom Key chooses Sora over Riku because he had the stronger heart.
However, in BBS, suddenly wielders can essentially force Keyblades to serve whomever they deem is worthy.
Who dislikes this? I dislike this, because it deprives the Keyblades of their mysterious sentience.
For those who like it, I'm interested to hear why.
You have a misconception here.
The Keyblade Ceremony does not "force" Keyblades to "serve" anyone.
Watch the scene where Terra does the ceremony with Riku again:
He holds out the blade and has Riku touch the handle.
By doing that, Terra lets his Keyblade "judge" if Riku has a worthy heart to one day wield a Keyblade himself.
It is also important to notice that both the intended wielder and the wielder granting the ceremony have to hold the Keyblade together at the same time and the granting wielder has to have master-level power (which is why such notions that Sora may have performed a ceremony with Jack Sparrow are false and can't work).
The ceremony is practically nothing but a letter of recommendation to put suitable hearts on "the radar" for a Keyblade as it is still the Keyblade itself that has the last say.
Despite getting the ceremony, Riku didn't immediately get a Keyblade.
It's even written down like this in DDD's glossary:
The heart must be proven before a Keyblade will appear in its master's hand.
and actually
shown with Lea, as despite getting the ceremony (either from Yen Sid or Mickey), he didn't get a Keyblade immediately but had to prove himself worthy of one Keyblade
choosing him.
Yen Sid even indirectly mentions it:
Yen Sid said:
It's clear you cannot teach a cat to bark. But Merlin and the three good fairies are aiding him in a place that's more...temporally flexible. My hope is that he can at least learn to wield it. He certainly has fire, so I suppose it depends now on how strongly it burns.
"Learning to wield it" can also be read as "prove himself worthy".
It can be assumed that saving Sora from Xehanort and his determination to "keep his promises" are what eventually convince a Keyblade to choose him at the end of DDD.