Once again I have to think CBR for the assist, and you can read a more detailed background of this entry at their recent post on the subject.
But basically it goes like this: Scott Lobdell thought Iceman should be able to have greater control over his appearance, but the X-Men editors thought that Toy Biz - who owned Marvel at the time - wouldn't go for the idea since they had recently released an Iceman figure and would want the figure to match the comics.
However, Lobdell came up with a storyline that would allow him to play with the appearance temporarily. In Uncanny X-Men #314 (May 1994), the White Queen takes over Iceman's body and shows him he's not using his powers to the fullest extent.
Toy Biz saw this design and was basically like, "Whoa! Do you know how many action figures we could sell with that design?" So in 1995, they released an Iceman figure with a more jagged look and the ability to "grow" different parts of his body.
Iceman was changed in the comics to follow suit, of course, but it didn't happen all at once. In X-Men #50 (January 1996), he still had a smooth look overall, but he also had SOME shape control. His ice form had hair now, and he could turn his arms into spikes:
One month later, in Uncanny X-Men #331 (February 1996), he got the jagged look from the comics.
It didn't stick, but few things do in comics.