點解外國政府成日要人民幣增值?

There is only one main reason:
To narrow down the trade deficit and improve the balance of payments between China and the other developed countries
As you know, China is an exporting country and a lot of developed countries record trade deficit against China. If RMB appreciates, imports from China become more expensive and trade deficit and balance of payments will automatically improve.
已發展國家要人民幣升值(人民幣不是八達通，appreciation是升值，不是增值)，主要原因是人民幣升值可改善這些國家與中國貿易所產生的貿易赤字及改善國際收支不平衡。人民幣升值，兌換成當地貨幣就變得貴，而別國進口到大陸就變得便宜，這樣便此消彼長，有利外國少買中國貨而中國多買外國貨，改善貿易赤字。