Ok, I apologize for my offensive language.
In all seriousness, however, you vastly underestimate the matchmaking time in Air RB. The top rank matchmaking is actually the most popular of all BR; if you rely on your experience with the top battle rating, you will inevitably be wrong.
Secondly, the supposed 10% increase in matchmaking time is the ideal change, and not practically obtainable. The actual increase to waiting time will be much higher You must remember, even in Air RB mode, that matchmaking can take multiple minutes. This is especially apparent if you play on less popular servers (such as the SA server), or on less popular battle ratings (Super prop and early jet BRs come to mind), or on less popular times of day for the servers you play on. The combination of these factors has an exponential, rather than a multiplicative, effect on waiting time.
Players will naturally be frustrated with the long times of waiting and leave the queue. This is directly visible especially in Simulator battle rooms, where often 2 or more times the players required to start a match (which is 2 on both teams) join and leave the room after waiting for multiple minutes. Meanwhile, the match never starts because there were never enough players in the room at the same time. This effect also occurs in Air RB. In reality, the actual time increase from a 0.7 BR would be far in excess of 10%, likely multiple times the total wait time per player, due to this factor.
This is just the mathematical result. Right now, in Air RB, we have BR from 1.0 to 14.0.
If you decreased the BR spread of matches to 0.7, and kept the max BR of 14.0.
That would be the same as decompressing the max BR to 20.0 under the current 1.0 BR spread system.