My recollection was the size got capped, and again I think it was 8500, because of a desire to prevent the university from scheduling major concert events there, which was perceived as being potentially injurious to the Civic Center and the New Haven Coliseum. But, that's from memory, so I could be wrong.
I'm pretty certain the original proposal was for somewhere around12,500 seats at an estimated cost of about $25-30 M. That was deemed too costly so UConn was told to redesign it and reduce the cost. The next iteration was for 10,000 or so seats but again, due to the time lag and rising costs, the cost was about the same as for the earlier design with 12,500 seats so UConn was told to redesign it yet again. Once again the size was reduced to save on cost and the design included 8241 seats for (again) about $25-30 M.
The real goal was to reduce capacity so the arena wouldn't compete with downtown Hartford and once that goal was reached with a capacity of 8241 seats the project was approved. Construction started in 1987 and we were there on January 27, 1990, to see UConn defeat St. John's in Dan Cyrulik's career game. Wow, we thought, he's going to be the best center we've ever had. Not the way it worked out, but he and Toraino Walker outplayed Mutombo and Mourning in the Big East Tournament semi-final that same year on the way to our first BE Tournament Championship.
Demand was so great seats were added around the entrances at the end of the 1995-96 season, increasing capacity to 10,027 seats. Two other small expansions increased capacity in 2002 to 10,167 and in 2023 to 10,299.