oil consumption can be done to many factors, you can turn a car that never burnt oil in to an oil consumer just by changing a small factor.
the brand of oil used
the viscosity
if its semi or fully synthetic
yes the car can start to burn more if the engine is wearing,the gaps on the pistons in the chambers can increase and allow more oil into the combustion process. also some engines burn oil as part of its own maintanence. the honda s2000 engine uses oil as does the RX8 engine, both due to the fact that they rev high.
oil consumption is not a bad thing as long as its monitored and maintained. i.e. if it uses oil check it and top it up.
if it burns oil you can try a thicker oil, some oils like magnatec are very thin, so going for a thicker oil can mean it won't get into the engine as eaisly or burn off as easily.
i some times think that people worry about an issue that might not be there, and actually its down to something as simple as the viscosity or brand of oil.
as a side note, as mileage stacks up on an engine especially high milers, it can often be good to step away from the manufactuers spec for viscosity and go thicker to match in with the age of the engine.