You don't always have to do something to make sense of it, when you already know the physics of the game engine it's not difficult to judge something new that you haven't played before.
I'm going to talk about this purely as a spectator, and it's entirely my opinion. As even though I really enjoy watching the classic Team17 map system, i've never cared for playing any form of Team17. The only time i've enjoyed playing Team17 is when Mablak was my partner because, well, it's Mablak and it's the teamwork that makes it fun with him.
To cut to the chase, i've recently grown to utterly despise Island Team17 as a spectator, especially after watching some clanners.
This analogy makes sense to me, it might not make sense to others:
Watching Team17 in dual layer cavern is similar to listening to a really well composed song.
It has a mostly empty beginning(collecting crates), as the song progresses on there are little bits of interesting action going on here and there(Some attacks/attempts to kill worms). The song finally reaches it's crescendo(the highest point reached in a progressive increase of intensity) where the most interesting action happens and you get to see the big SD plays happen.
Island Team17 on the other hand...
As always, it's still nice to see creativity that the players come up with, however it's really lacking that Sudden Death intensity which makes Team17 absolutely shine in my opinion. I can see why it's fun for Team17 players who enjoy Battlerace mechanics and chuting around, having a new environment to adapt to, that isn't really that fun to watch though for me personally.
As a spectator it just looks even more luck based, this doesn't mean it doesn't have skill, it still takes a lot of skill to master the weapons, get around the map quickly and think of creative solutions on the spot. Though at the same time the map is just so open it doesn't feel like a controlled environment at all. You don't have anywhere near the same level of protection and map control because crates aren't as defined by the map on their arrival. Then there are way more airstrike weapons and possible attacks, even when you get blocked there's a high chance you will have picked up and air strike weapon, which i've seen multiple times already. This scheme, more than ever feels like getting the right weapons at the right time will give you the win, more than dual cavern.
Maybe if we had the ability to see what the players actually have, then as a spectator you could have an extra level of excitement, like watching a soap drama when you know information that they don't know about each other, and the tension you feel as it plays out.
I feel like any average player who kind of knows what they are doing can get lucky and beat a top player, which is also why I believe Team17 in general is more popular, it's easier to play and win. It's more fun for casual players.
I'd like if the most experienced players could go into great detail explaining, in their own words, the benefits and reasons to enjoy this scheme. Maybe i'm looking at this scheme with a closed mind.
Right now though, i'm just glad you are allowed to refuse Island Team17 in the Allround League.