Hate to keep on posting, but the more that I think about it, I think
you are partially correct - the City worker that works around Bank and
west of there will choose your Waterloo/Bank route. But any City
worker that works anywhere along the buildings along Bishopsgate (and
that's where all the tall/large buildings are, think the Broadgate
complex, that new Heron Tower monstrosity (due to be the tallest
building in London, already under construction), the "Bishopsgate
Tower" now under construction, Tower 42, etc - they are all over by
Bishopsgate - or even further east (think the Gherkin Building (the
Pineapple building), the Commercial Union building, Lloyds of London,
etc) - if you don't want to hike, then a bus down Bishopsgate sounds
appealing.