Here we go again with DP revisionist history. There has only been one issue people "bitched" about regarding Metal Slug Anthology.
The main complaint isn't the price, it's the general shittyness of the Wii version controls vs. the PS2 version. If someone likes the Wii version of MSA...great. However, the reality of the situation is this...the PS2 version controls better. People can buy whatever version they want. It's not really that big of a deal overall. People who have played both versions (i.e. me and others) are simply offering advice.
It's not a matter of opinion. This is a fact. If anyone disagrees, please tell me how much time you've spent playing both versions.