I wrote this a while ago but I might as well post this.
Personally, I think that they could have done better animating it--really, I do. Especially when you compare to previous cartoons and comics that have had long-haired characters. At this point, due to the horrible quality of its animation, I really think that they should have just stuck with his old style. I do admit, though, that were scenes that they did partially well but could have been done better.
Now, who am I to say that they could have done better? Seriously, I know how to draw and been drawing manga for eight years. For those of you who've seen my works in the FanArt section, I know it looks like I can only draw Winx Club-style but if you visit my DeviantArt account and go through my gallery, you'll see some of my manga pieces. If you haven't seen my Winx Club drawings, here are some examples: Flora and Roxy. Here's a manga piece, just in case: link.
This is my interpretation (a manga one) of Helia and how they could have possibly styled his hair:
Next, if Helia is working at a bar (the Frutti Music Bar), shouldn't he tie his hair up in a ponytail for sanitary reasons considering that he works around people's food? Do you like finding hairs in your food? At least, that's how I think it works.
At any rate, the animators failed epically when they first tried to introduce his new hairstyle in. Aesthetically, it's not pleasing anyone. His hairline is a third of the way up his skull, first of all and that pretty much destroyed everything.
Let's admit that animating characters with long hair is bothersome for animators (look at what they did for Katara in Avatar: the Last Airbender: pilot episode commentary). Anyways, it's tiresome to animate considering that Helia has to fight hand-to-hand for a fair amount and there's probably a lot of hair movement to consider when they animate. When you think about it, it sounds like super lame reason if we look at other shows and comics such as Neji Hyuga from Masashi Kishimoto's ever popular Naruto:
This ninja has freakin' long hair (that's tied in a loose pony tail in the back) and he gets into some serious and epic fighting during the series! I'm surprised that none of his opponents have pulled on it get the upper hand or try to cut it. As far as I know, he does not have a thing for hair and more or less wears it that way out of tradition in his family.
Now let's look at the statue version of Yasha from Clamp's famous manga series Tsubasa: Reservoir Chronicles (chapter 54):
Okay, so he's a statue in this picture (and he happens to be a god). Towards later in the series the main characters of the comic travel into some alternate dimension where Yasha is a real person and looks just like that. Point being, this is pretty much the same hair style as Helia's except much longer.
The animators really could have done a better job.