The race is not underpowered by any means, MC, Naniwa, incontrol, KiwiKaki, Tyler and axslav off the top of my head really have shown great results in tournaments because they understand the race. Saying that protoss is underpowered because master level+ protoss find it difficult to cheese masters+ doesn't mean the race is imbalanced.
I'll leave to one side what some people might interpret as a general insult to Protoss players.
I don't think the issue is "people know how to respond to cheese now", as you appear to be suggesting. If you watch the games from the GSL super tournament, the best results in the round of 64 came from players who used relatively gimmicky timing attacks (eg Ace and HongUn). No disrespect intended to these players - you need to do what works in the circumstances. The Protoss players who played what we might consider a "solid macro game" seemed to be the ones who did not advance.
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