I think it's because Leicester has suffered from 150 years of civic vandalism, being under the tender care of the whig/liberal nonconformists in the 19th century, being gutted by trendy architects in the sixties and now this lot.
In any other place, it would probably have gone unchallenged, it's just that Leicester has so little of historic interest left. The bridge was part of a footpath the "Great Central Way" which led out into the country and the "Pump and Tap" a thriving local.
The bridge was , probably deliberately, allowed to go to rack and ruin so the Council could claim it was unsafe. Local people regarded it as the "gateway" into the West End of the city.
De Montfort University have alreday scarred some parts of the city centre with architectural monstrosities and the town is beecoming all "glass and glitter" and resembling a Mondriaan painting.