Have you purchased all available land? If not, why?

I have 12 parcels of land and 4 parcels of water yet to be bought.
I've been playing for a bit over a year and still don't have significant cash reserves (about $500K after buying the slaughter house). I will eventually buy the rest of the land, because sometimes I just buy land because it's something to do.
At present, I have about 11 parcels of vacant land, as well as a house farm of fifty blue houses with yards and streets that will be progressively retired to make room for other things.