Steve Jobs was obviously holding Apple back, only just recently did we finally get a 4 inch screen, 4G LTE, and (keep in mind he publicly decried this form factor) an iPad mini 7ish inch tablet
It's brave to say Jobsy held Apple back - he brought Apple back from the ashes.
Jobsy supposedly passed on much advice to Tim Cook - on where to go with the next few models. Jobsy may not have been against 4G LTE and a 4 inch screen - he may have recommended Tim to go down that path.
About your assertion that the 4inch iPhone is a Tim Cook idea, I doubt it. It was probably in the pipeline for 18months so I'm sure it was signed off by Jobs. Next years products are going to be the first under Tim Cook's reign.
And Steve also said that video on iPods was a stupid idea.... a year before he introduced a video iPod (so Apple must've been working on it even as he made that statement)
Jobsy supposedly passed on much advice to Tim Cook - on where to go with the next few models. Jobsy may not have been against 4G LTE and a 4 inch screen - he may have recommended Tim to go down that path.