Before people power things close to arena caps, what do you have closest to 2500 or 1500 cp?
Answers
There have been countless show your first page threads on this message board...players in my city might lose but a few of them will say, "I have 300 rare candy and 3mil stardust." Or: "I'm waiting for 98-100% before I power _____ up." (Not every player plays hardcore DPS+TDO, a better matchup might be the lesser matchup).
***I'll probably pick 3 of these in the unlimited area
You missed a lot. These lower CP tiers create a much wider opportunity of participation for weaker Pokemon to compete, thus expanding the pool for a very interesting meta (in theory). These arenas are where a bad IVs Cresselia may find actually be a good choice and the Regis might find some great usability.
The unlimited one will probably just become an extension or offshoot of the current gym/raid meta, of which a lot of players are tired to exhaustion. All the usual suspects will reign supreme now and forever so almost no one is showing evident excitement over it because the most requested overhaul aspect of the battle system has always been a method to diversify our options (by implementing abilities, status effects, you name it). Since CP is a simplification of stats that help indicate general strength, limiting tiers by CP will help standardize which species will be eligible to battle simply because some powerhouses like Mewtwo or the weather trio won't have that much of an advantage over considerably weaker foes that can reach similar strength (albeit at much higher levels) when limited to a certain max CP cut off.
So basically no one is talking about the unlimited one because many perceive it already as the presumably "boring" and "predictable" option. I already have legions of Pokemon that I will be able to use right away on the Unlimited tier, whereas I can inject some new excitement into the game by preparing top-dog teams for the lower tiers