It seems you don't understand how leading works in ice dance.
I will admit I have no experience whatsoever of ice partner dancing. But I do have lots of experience in swing dancing leading and following, and I can tell from just looking at ice dancers, that whatever you call leading is something entirely different from what I know as leading. In fact, in the vast majority of case, I don't see leading/following at all. Please enlighten me, what is it in ice dancing, and what is it's purpose? And whatever it is, why couldn't you live without it, since it's all totally choreographed anyway?
#1 Improvisation is a terrible idea for partnered ice dance. It's just dangerous. The speeds are much higher. The lead changes every lobe or turn, which is every 1 to 6 seconds and occurs irregularly. You can't improvise when the lead changes that fast.
Maybe not, but that leads to question about the necessity of speed, and turning everything into a high speed perimeter dance. Sure speed is fun and all that, and works for certain dances, e.g. viennese waltzes. But there's obviously a cost. And one cost is the ability to be able to safely lead/follow. This BTW is the funnest part of swing dancing. The physical communication, the exchange of momentum, and the creation on the spot of something amazing and fleeting. Ice dancers really have no idea what they're missing.
I don't see why improvisation is better than something that's practised. It's just different.
Improv in partner dancing is better, because it requires actual real real-time communication between the partners. Improv is a conversation. Sure you can have practised recited conversations, (e.g. like a theater play has), and we all know it's not really
made up on the spot, but the magic is that it's plausible that it could have been.
2 actors alternatingly (or worse simultaneously) reciting lines that don't form a conversation is pointless twaddle.
That's the current state of ice dancing, at least that's how it looks from the spectator perspective.
#2 It isn't difficult to tell the type of music for a skilled dance team.
Any unskilled person can easily spot a tango done on feet. You'd have to be an ice dancer yourself to identify an ice tango. Ice dance really does look that generic. It's almost considerable as a single unique style by itself.
#3 If you want to go slow take your skates off. Going fast is the fun part.
So, why not give up the ice dance lark and just do speed skating? Does ice dancing have nothing to offer without the speed? At this point, I'm wondering....
Again, in ice dance the lead changes every lobe. The difficulty of leading is based on the tempo and number of beats per lobe, not how fast you are going. I have had no difficulty with lead when dancing at high speed.
Whatever you are calling lead, is clearly not what I'm calling lead.
You lead in real dancing anytime you want to impart linear or rotational acceleration/deceleration to your partner (which is pretty much continuous in swing dancing), or in more specialised cases, it's a forewarning that you're about to do something special, so your partner can do something matching and special too. It's exactly a communication of intentions. Which is why improvisation works seamlessly when true leading and following is being done.
#4 There are no "rhythm" dances in ice dance.
Indeed there currently isn't, but there COULD BE. e.g. something like the original clip I posted. Not claiming they're the possible pinnacle of the form, but they're the first example I've ever seen of actual partner dancing on skates, that wasn't a smooth ballroom based dance.
Just because an ice dance has the same name and music as a ballroom dance does not mean they have (or were intended to have) much substance in common. The inventor of the ice dance may have had no knowledge of the ballroom dance. Think of ice dance as skating which has been influenced by ballroom dancing (overwhelmingly waltz), not as dancing on ice.
Which is a shame. It could be so much more....
Which would increase the excitement. Wouldn't stop everyone.
Certainly didn't stop the couple in the original clip I posted.
In practice, Ballroom and Social are often choreographed too, especially at competitive levels, or sometimes for wedding dances, in which case lead/follow no longer refers to the routine itself.
Swing routines for exhibitions and competitions are often totally choreographed too, but they still properly lead/followed, to the point where the leader could trivially change something in the middle, and the follower could and would just go along with it, without anyone even noticing. Like a polished jazz band can seamlessly deal with any place the tune goes.