Okay, so you keep trying to knock on Del Rio for having no character other than being a smug rich guy - what exactly is Ziggler's character, other than being a smug dick head?
Seriously. Ziggler has WAY less going in the character department than Del Rio, and Del Rio has been around way less than Ziggler. Ziggler's entire character is based through Vickie. Ziggler has no character of his own, other than generic "smug athlete".
You can knock Del Rio's feud with Mysterio all you want, but that feud has been way more meaningful than anything Ziggler has been in. Ziggler hasn't even been in a feud. It's been random face opponent after random face opponent with absolutely no build what so ever.
His 2 most meaningful "feuds", if you can call them that because you can't, were a 2 match series against Daniel Bryan (or was it 3?) that didn't even have any belts on the line, and a 2 match series against John Cena that had absolutely nothing to do with Ziggler or the IC Title, and everything to do with Vickie Guerrero and Cena v. Punk.
Yes, he's a good in ring performer. I give him that. But a main eventer has to be more than that. A main eventer has to be a good in ring worker, as WELL as a good character. Even the examples that people cite like Bret Hart, guys who weren't necessarily The Rock or Austin on the mic, they had good -characters- that you had an investment in. These guys were more than just good in ring workers, or they were more than just good talkers. They were good -CHARACTERS-, guys that you believed could be main eventers and win any title in the company against any guy in the company. That's something that Ziggler isn't. He has no character. There's been nothing to develop Ziggler as a character to push him into the main event. He's a good worker. That's it. He's had zero meaningful feuds, he's had zero development as a character. He doesn't belong in the main event.
At this point, an IC title feud for Del Rio is a step down. He's already feuded with guys higher on the food chain than Kofi. WTF is a feud with Kofi going to do, when he already dominated the **** out of Mysterio? Del Rio needs to be the one getting the "Royal Rumble" test against Edge, not Ziggler. Ziggler is the one who needs to be in the Royal Rumble, and have his character built for a few months until he wins a MITB at WrestleMania, then can dabble in the main event for a bit, while building that main event credibility. Del Rio already has main event credibility. Ziggler is nothing more than the most recent random IC champ, who's had a handful of really good matches that were built on elements that had absolutely nothing to do with him.