While it makes sense for the likes of K. Rool and Palutena, both characters that have varying amounts of hints/teasing towards a playable status, I really don't see the argument that Ridley won't be shown at E3 because he will be "expected." We must remember that beyond this thread, the vast majority have taken Sakurai's bait and believe that Ridley is confirmed as a hazard, so while it wouldn't be much of a surprise to us should we see him playable, the rest will undoubtedly be shocked.
Also, I can understand not revealing all the big name characters during the time since last E3, but, as I've mentioned countless times before, this E3 will be the last big advertising push the games will get before the 3DS version comes out where at that point the entire roster, aka the main source of hype, will be fully unveiled. With that in mind, why wouldn't Sakurai show off fan-favorite additions that many are clamoring for? Sure they would be expected, but people will still go nuts anyway, not to mention the reaction(s) will be bigger for well known characters that most are aware of/are supporting then random obscure selections (WFT).