I wouldn't attribute too many of Hull's difficulties to the collapse of the fishing industry. It was a major employer, but really only on the south-western side of the city. Its collapse wrecked Hessle Road, but the contraction of the railways and the town docks has had more of an effect on the city as a whole.
To be honest (and I'm sure this point of view is unfashionable, but so what?) the lack of fancy shops is something I like about Hull. Far too many cities of Hull's size are just clone towns these days: the same dull chain stores, no streets of shops, no market, no variety. I like the fact that that hasn't so far happened in Hull. I loved Newland Avenue when I loved around there, because I could do all my shopping down there and rarely needed to go into a dull supermarket. A street like Newland - a self-contained shopping area composed mainly of independents - is such a rarity these days, and the shops down there are very good.
I'm not against more major stores setting up in Hull, but if they threaten the independents I don't want them. I think it's sad that Tesco have been allowed into the St Stephens development, for example. It'll be the death of a lot of shops in the centre and up Spring Bank. I'd have left them to fester in their drab shed on Orchard Park and allowed the centre of the city to keep its individuality!