Today more and more ads are seen on television. There are several different mediums through which to advertise: print (magazines, fliers, newspapers), television, radio, etc. A decade ago more advertisements were in print or on the radio, but as society progress the bulk of ads are now viewed via television.
The reason for this trend is that more time is spent in front of the TV than almost anywhere else. The television draws viewers in for 'hours at a time, leaving little time to do other activities such as reading. Also, advertising on TV provides a captive audience and increases the likeliness that the viewer will absorb the ads.
I do not think the growing trend of watching endless hours of TV is a healthy one. However, the goal of advertising agencies is to reach as many people as possible, and that is exactly what they are doing by advertising on television. Though watching mass amounts of television is not an ideal situation, it is indeed a fact. Until that fact changes, neither will advertising methods, nor are those of space and freedom to enjoy a more relaxed lifestyle.