De-centralization of roman state

[Robert Vermaat]

In the 3rd century, possibly even earlier, the roman empire became less centred on Rome and Italy. Industry, trade, art, recruitment etcetera, to a large extent, took place in the outskirts of the empire. Cities like Leptis Magna booming.
Of course this had impacts on Rome itself. Why did these changes occur and what was their actual implication to life in the empire?

If you are looking at the 3rd century with all the fighting going on, this might be a natural development. With all the usurpers it was natural that Italy could no longer be the focus and therefore, regional capitals flourished.
On the other hand, by the 4th century we see a backlash in the sense that the Roman bureaucracy became even more centralized, even when the empire was divided into 2 parts and the military and military command was split from the governors of the provinces. In fact the civil service became top-heavy.