Why are the oil companies not keeping their refineries up to date and why are they not improving their output?

The oil companies are saying they can pump far more oil than we have a demand for and at the same time they are saying their refineries can not process the amount they can pump. There seems to always be a reason why one of the refineries goes down and if there is not a better reasons for the refinery to be shut down they do so for alleged maintenance.

Why don't the companies improve their refineries to prevent break downs and to increase their output?

Why are so many of the refineries positioned in areas that are frequently so negatively effected by adverse weather? Why would the Keystone Pipeline be run into the Texas refineries that are already subject to weather shutdowns and by increasing the dependency on those refineries make them a major threat to terrorist activities?f

They are in a position to make more money by processing less. They can reduce their overhead by cutting back on production, lay off a handful of employees, reduce their operating costs and kick the price up thus making a larger profit.

Why - with the alleged intelligence of the Oil Company management, can they not improve their ability to increase output and to improve the refineries efficiency and safety?