Photoshop has all the tools needed to do pixel art... and then some. The only reason I don't use it is because it is a memory hog and takes a while to start up... not what I need when I want to quick push a couple blocks. The simple answer to overusing Photoshop's tools (and it's not just pixeling that can be abused by overuse of photoshop)... is to just not use anything other than 1px brushes with no aa and the fill tool. Of course there are plenty of tools like selections, layers, colour correction... which, when used by a knowledgeable individual, can save time and still be pixel art.
Photoshop may be overkill, in terms of features needed for pixeling, but it has the tools you need and a good artists knows how to use the tools correctly.