This kind of crap has to stop.
The phones do not have limits in space.
The guy says it's the power, but it's mostly the size.
And whether you guys like it or not, the mobile devices can output decent graphics.
Not to mention Sonic 4 Ep.1 used a different graphics and physics engine from what Episode 2 does, so bringing up "OH, EPISODE 1 WORKED, WHY NOT 2?" is totally irrelevant.
Regardless of what SEGA's given reason, it's probably too big (because people make games without thinking in restriction when making multiplatform, imagine that), the Wii is on its way out and nobody really uses WiiWare anyway.
Like TheWon said, it's not like it's on PSP or anything. I wouldn't be surprised if a complete Sonic 4 collection came to Wii U.