Hmm, true. success is 6 bullets. So pistol with one ammo dice added mean 7 bullets for that ammo dice success. every time. Initially I don't see an issue with a house rule of roll ammo dice to see if you get ammo hits and reroll to see bullets expended, or the just rerolling the success to see how many bullets the success was.
As @Vcutter already said, there was a post about that recently. The problem with de-linking ammo dice successes from ammo spent rolls is that you need to roll more dice. YZE tries to avoid that at great costs. It might not be everybody's cup of tea, but that's what it is.
Also, remember, each round is up to 10 seconds long. That's a lot of time in a firefight. Hence it's perfectly okay to spray a lot of bullets down range.