You mean the "Potunghau-lization" in GuangDong??
I don't know why.....Did the PRC government want to unify the pronunciation and wordings of Chinese language? That's stupid. UK has the size of Guangdong province but they have more than 20 accents of British English........
Well, I'd like to say again that you may not agree with what they do, but they are not stupid. (OK, may be they are in this case...)
I can see perfectly why SOME in the government would like to put Putonghua first. See my Tibet story below. The reason could be totally legitimate in a macro view. Again, in this case I I do not think it's necessary, and I hope the idea does not come from the top of the central government.
When I went to
Tibet in 2004, one of the most striking scenes is how with ease kids would come to us asking for money. At the same time I can see that it's a very common practice to hand out small money. (Read my story, especially 32 & #7.) During and after the trip, I was thinking about how the Tibetans' may improve their lives, material well-being wise. And I think one of the ways is to improve education and integration with the rest of China. And one of the key for the improvement is learning to speak Putonghua, learning to read Chinese. I can see the the better off Tibetans in Lhasa are those who speak Chinese.
You remember our Chinese history lesson, where 秦始皇 was mean and ruthless, yet at the same time he did something of positive and of long lasting value to China - that is the unification of writings and measurements. While at the expenses of the minorities, the standardization allowed easy of trade and literature. I don't think anyone can argue against these long term positive effects, especially we are now still enjoying the benefits.
So in certain situations, standardization (or globalization-like policy), including language, could bring very positive long term benefit.
However, in the case of Cantonese, I think it's not necessary and may not be possible. Cantonese speaking regions are well developed economic wise, and Cantonese speakers, while may not speak Putonghua well, can read Chinese as well as any equivalently educated person in China. The existence of the Cantonese culture does not interfere with the grand national development. In fact the study and preservation of Cantonese can be of great value to the study of Chinese literature. One of my tea friends who teaches Chinese literature in Baptist University once told me that Tang poems 唐詩 sound better in Cantonese when reading outloud, because Cantonese has long root and influence in early Chinese language.
So, long live 掉那媽,頂硬上!