Agreed with this last. There's a general economic expansion at this time and expanding the development of agricultural lands is a part of it. It's little different than the expansion that took place in Catholic Europe during the 11th century except that the catholics were expanding into new areas where in the east it was expansion into areas that had been abandoned due to earlier depopulation. That usually doesn't signal population reduction.Finally, about population density, I'm not sure I buy it. There are numerous examples of towns across Anatolia bursting out of their acropolis and recolonising the old Roman-era settlement with increasing frequency from the tenth century onward. Now, some of this growth can probably be explained by peasants from the countryside moving back into urban centres that were no longer targets for annual Arab raids, which could mean a (relatively) more empty countryside, but I do think that the idea of a depopulated Anatolia by the time of Romanos IV is probably a myth.
It should be noted that evidence indicates that while sharecropping was growing in the period, it still provided the share-croppers more wealth than previous time periods and in some cases might have been a better deal than owning your own land.