Why has tv reception been changed to digital?

In digital there is a signal threshold below which dropout (pixelation) occurs. When an analogue signal degrades the picture just gets 'snowy'. However, digital reception which is running alongside analogue is at quite a low level to prevent interference with the analogue channels and appears more susceptible to weather interference. When the analogue signals are turned off the digital signal is boosted to give maximum coverage and will deliver a better service all round.