Why was this done?
Conventional FIAT currencies allow governments or banks to print money and cause inflation. In Bitcoin's case, the total supply will be maxed out at 21,000,000 BTC. Printing extra money causes inflation, if there is no extra money printed, the value of the Bitcoin should increase as the demand will rise (more people will start to use Bitcoin) and supply will lower or stay flat (no more Bitcoins are "printed"). This makes Bitcoin similar to gold, which has limited supply and cannot be "printed" or artificially created.
How often does this page update?
This page updates the predictions automatically without refreshing, on every new block mined. Unlike most countdowns, it is not a hard-coded date or set manually. Its an accurate mathematical prediction based on the average time taken to mine each block on the BTC network. This prediction is algorithmically updated when a new block is mined, roughly every 10-15 minutes.