I'm with the idea of maintaining the difficulty of the IC's chaingrabs, and leaving them in SSB4, but simply setting a limit on them. How many times you can chaingrab could either be determined by some sort of damage limit, or by the number of times the opponent is grabbed. Meaning perhaps once 50% damage has been done by the chaingrabbing process, the opponent could be turned into an icicle and thrown into the air, forcing the ICs to either combo into it or back off somehow. Same idea with the "# of grabs" limit.
(Yes, I'm basically making a Frankenstein out of the ideas I liked the most in this thread)
Once this is done, you could probably up the ante when it comes to the IC's general attack priority and maybe even grab range. Have a sure way for them to desync as always, and you've got yourself a fun, awesome, mostly balanced duo. Just like they should have been in Brawl. I actually think they were fun and balanced in Brawl, because you mostly only see devastating CGs in tournament settings, and I'm guessing that these settings are more regulated and if it becomes a problem, then the ICs could certainly be banned. PLUS infinite chaingrabs are impossible in multi/party brawl unless people just love watching infinite combos that much. Also, there are known ways to avoid that tiny grabrange from getting to you if you're careful enough, or use certain abilities. (Like Snake holding a grenade so that if grabbed, it will blow up in his and the IC's faces)
Basically, Ice Climbers should be an easy fix for SSB4. I don't see a reason to remove them as they're unique (and adorable, as some have remarked), and potentially they are one of the PILLARS of what Smash Bros is. I mean, two characters being controlled at once? Desyncing? Chaingrabs? Classic characters from the 1980s? An immense set of amazing moves that can be performed because of desyncing? Split-second timing skill "split" between the two characters? Where else do you see this sort of stuff?
The Ice Climbers deserve to be in SSB4, whether they're completely redone somehow or they're quite the same with the needed, SMALL tweaks made to them. I don't see why they should be kicked out instead the boring, near-clone characters first.