This is brilliant small town thinking.
We build a big arse stadium to attract more headline acts, so said acts can come here and still make a good quid, then we reduce the capacity for one of those acts, due to the location being craptastic for traffic on one of nights you'd want to use it.
We already have that reduced capacity stadium, that hilariously enough, has transport infrastructure all around it. And eating and drinking establishments within walking distance.
If this isn't a Simpson's episode somewhere, it should be.