I don't see why you're so happy about removing so small and fun to use? I love honking my horn when I just want to mess around with the game's soundtrack and just being obnoxious in general. Might as well remove headlights and some character voices altogether if being pointless bothers you so much.
I prefer the character specific horns, makes the character feel more unique. Though I do miss the Super Mario Bros. horn jingle from Mario Kart Wii.
I prefer it if characters have individual horns, but a hybrid could be a nice touch. As in, selecting certain vehicles will also apply certain filters to the horns, so perhaps some vehicles will make the horn sound like chiptunes, or some would give it an echo effective.
During the release , i played a lot as Peach until i unlocked Rosalina ; I liked to use the horn because at the time i though it was a cute addition for each character.
Then i Unlocked Rosalina , and was excited to use the horn and then i just heard the same sound as Peach's
Which led me to think that EVERY HORN WAS THE SAME.
...
After Playing with other characters i realised that Nintendo literally copy pasted Peach horn into Rosalina and i got super upset.
What a sad sad day. I Hated Nintendo so much that day.
Even friggin Baby Peach uses a unique horn from Peach lol.
I'm glad Baby Luigi has a unique horn, even though it's essentially a lower pitched Baby Mario horn, which even so, says there's at least a discernable difference between the two
Too bad you can only voluntarily honk the horns in Super Circuit, Double Dash, and MK8.
I don't remember about MK7, but I do know that DS and MKWii only had horns blow when the vehicle got bumped by another.
In different parts among the fans, there is a tendency to celebrate a character's anniversaries in multiples of 5 (if they are old enough), so I made a list of a select number of characters and their debut years:
Years ending in:
1, 6: Mario, Pauline & Classic Donkey Kong/Cranky Kong (Donkey Kong, 1981), Mallow & Geno (Super Mario RPG, 1996), Professor E. Gadd (Luigi's Mansion, 2001), Dry Bowser (New Super Mario Bros., 2006)
2, 7: Donkey Kong Jr. (Donkey Kong Jr., 1982), Wario (Super Mario Land 2, 1992), Bowser Jr. (Super Mario Sunshine, 2002), Rosalina & Captain Toad (Super Mario Galaxy, 2007)
3, 8: Luigi (Mario Bros., 1983), Birdo (Super Mario Bros. 2, 1988), Koopalings (Super Mario Bros. 3, 1988), Toadette (Mario Kart: Double Dash!!, 2003)
4, 9: Princess Daisy (Super Mario Land, 1989), Modern Donkey Kong & Diddy Kong (Donkey Kong Country, 1994)
5, 0: Toad, Princess Peach & Bowser (Super Mario Bros., 1985), Yoshi (Super Mario World, 1990), Dixie Kong (Donkey Kong Country 2, 1995), Baby Mario, Baby Luigi & Kamek (Yoshi's Island, 1995), Waluigi (Mario Tennis, 2000)
You could make an argument that the old Donkey Kong and the new Donkey Kong are the same, but the common interpretation is that both characters are different, so I assume that modern Donkey Kong is a totally different character that is newly introduced in Donkey Kong Country.
Anyway, even though it's likely a coincidence, I liked how the Mario Party 3 character selection screen is ordered in a way that orders the characters in their debut years:
Mario (1981), Luigi (1983), Peach (1985), Daisy (1989), Yoshi (1990), Wario (1992), Modern Donkey Kong (1994), Waluigi (2000)