Why they chose demolition?  Let's see, what did they tell us at the time over 70% majority objections within the students, faculty, local residents AND alumni? - Hughes was too far away (at 3 miles on the foothills campus), Tie students to campus (so an on-campus stadium while student housing is now miles off campus, some with no grocery or other necessities located nearby and with continuous shuttles to campus), football fans wanted an on-campus stadium (so they can bring their children to the now radically changed campus), donors would pay 100% (they borrowed 100% so now the $229 million plus $14 million annual debt service) etc 
Before the stadium bombshell , President Tony Frank started increasing funding to the football program by millions per year while the faculty were on pay freeze for 4 years and they deferred maintenance on Hughes (a publicly owned  facility) and took the $3 million annual profit elsewhere.  CSU engineers had deemed Hughes sound. Renovation costs est @ $60m.