I think it's down to general profiles, lack of ambition and variance - we celebrate old buildings, but Primark is very different to the other remaining bastions of ye olde Belfast. It wasn't the same box shape "but with simply excellent detailing!". It had a clock face on it. It mixed styles. It tried something that probably caused tutting in those halcyon days.
It also is the clear commercial switcheroo of buying land, putting in glorious render, get planning permission, selling on for profit with planning permission, new cut down render and boom, another office with To Let signs for 2 years - that whole process is starting to grate when we get generic buildings, and clearly the City council, planners, and business people are profiting off a finite resource that isn't being driven by public need but by greed and starry eyed powerpoint proposals.
I'm against the Sixth for the enormous loss of the impromptu venue space, as well as sensible potential for it to have been a new student union. But taking that away, and we're in a world where they never turned it into a music venue, on the design alone I don't like that basic basic design. It's like the North St one too, which I don't like for the same reason. It's so desperately uninspiring (a phrase Kevin McCloud would be proud of).
Thanks for pointing out the signage Bug - and yes if that's where it is retained, as a nice nod to its 'heritage' (yes an orange sign with 60's font can be 'heritage' - eye of the beholder and all that) then cool - a painless little touch that would raise a smile.
PS the one bit I like* about the Sixth, which is actually an element that is achieved with much better results and impact on the Merchant Square proposal, are those set back windows under the vaulting flying buttress-esque pillars in the top left. Reminds me of Moorish/Middle Eastern architecture for some reason a little. I mean, it's still a box, but there's something interesting about playing with the space like that. It's that difficult-to-put-your-finger-on element I also liked on the front of the current Queens student union and those circular holes in the awning.
*to be fair, it's the only 'flair' in an otherwise box that could be a student accommodation honestly, you wouldn't be able to tell.