I disagree.  Although I'm aware of Rob Liefeld's disapproval at the character being used like this, at least Shatterstar is being used in a new & different way.  It's the first time he's shown any kind of development.  Comics have evolved passed the steroid-pumped killers of the 90's, so we need more than just another angry young man with swords. 
 
While I'm not crazy about the way that Shatterstar has been turned into another Captain Jack Harkness type character that wants to bonk everyone & everything, at least it gives him more depth to his character.  And more importantly, he's actually IN comics.  And on a regular basis.  He's been in limbo for too long.

No. Shatterstar's sexuality isn't holding him back. Only the writer can do that. Shatterstar is just a character. The writer is what gives the story to the characters.
 
I've been a big Shatterstar fan since his 1st appearance in New Mutants. I still have his 1st appearance issue and most of the X-Force vol 1 issues with him in it.
 
I don't think his character development of late is directly tied to his sexuality. Poor writing and lack of good character development doesn't depend on the  character's sexuality. The fact that you brought that up as a potential reason seems kind of strange. If a writer is doing a poor job with a character, then the writer is doing a poor job. <sarcastic>Maybe the writing is bad because Shatterstar doesn't have his long pony-tail anymore?</sarcastic> 
 
The quality of Shatterstar's character depends on the writer and the editorial staff's direction and intent for the character.  I'd like to see Shatterstar get a bit more attention and more fights to show off his skills, but it's hard for one character to get that much of a re-write/focus in team books unless they do a one-shot or limited series with him as the primary character.
 
I picked up the most recent issue of X-Factor (Second Coming: Revelations tie-in). I'd prefer to see him in more of an X-Force or X-Men title than X-Factor, I just don't like the X-Factor title for some reason that I just can't figure out. Maybe after the X-shakeup of Second Coming, he'll get reassigned to a different X-team.

He's never struck me as anything more than another part of the 90s anti-hero glut.  Not keeping up with the x-men much, I hadn't heard of Shatterstar's homosexuality until this very thread.
 
And even after that realization, he still doesn't strike me as anything more than a product of the 90s anti-hero glut.

by making him gay, he's become relevant and not the 2d "gladiator" he started out as 
I'm quite amused with this direction

There're a whole lot of charaters who don't get much page time.
Shall we make an excuse for them all?

Rictor and Shatterstar are my favourite couple at the moment
seriously, they are so cute!

why does his sexuality matter?

I think his bisexuality at least makes him interesting.

What's even more interestng is that he very well may be Dazzler's son! Yay for strawberry blondes! lol

Every damn time... I keep thinking people mean the mod of the same name ;)
 
Anyway, I digress... Shatterstar's homosexuality will probably help with the character's evolution, but I hope that it won't define him.

I feel like Shatterstar was just another victim of 90s edginess.  He had a really "kewl" look, but like Cable, he didn't have too much going for him beyond that.  Luckily for Cable, he got in the hands of some talented writers and they ended up making the character very interesting.  I think Shatterstar's homosexuality was an attempt at doing the same for him, but unfortunately the character just hasn't found his time for a resurgence yet. 
Let's hope for fans that he eventually does get his just due.

being a person that owns nearly every single comic that shatterstar has appeared in, i find his current state to be interesting.
now, the fact that i own almost every comic he is in does not mean i was a fan of his.  i was a fan of new mutants and x-force and now a fan of x-factor.  i used to find shatterstar's character extremely boring and only there to attack things and then disappear into the background again.  at least now he's evolving.

No, I think it makes him 110% more interesting. Not only does a subject of controversy sell, but Star is still amazingly cool. And he's gay, but still a hardcore gladiator, coping with modern life on earth. He deals with both love and emotions and life, and also his needs to fight and kill. Star is not just a gay dude in a comic book, unlike SOME, who will not be named...anyway, he has a fascinating history and has room for a lot of character growth, who just happens to be also gay (or bi, whatever). 
 
Plus, I mean, Peter David is doing an AMAZING job writing him. X-Factor is great, and it's hard to get competition on writing a character when there is already someone doing a great job. Like how no one can really write X-23 as good as Craig Kyle. 

Yep, because Asexuality is super common and super popular in today's society. Damn more than the majority of writers who worked on him, one who made him, all like in the 90's thinking about taking him in this direction because he is a character expanding and with that expansion new creative changes are called for, damn Peter David for just suddenly making him gay, even though in books long before writers were dropping hints. Damn them, damn them all to Hela! 

I know that a character's creator can be pretty touchy with this kinda of stuff, but he's kind of acting like a baby about it. Suddenly turning a character against their sexuality is a big step, its not like changing hair color thats true, but Rob is behaving ridiculously childish. If he gets the chance he'll undo it, yeah real mature. No one cares that much about Shatterstar, he's 90s, but they do now, because of his character revamp and his openly gay relationship, with another character who is also boring, if it wasnt for his open sexuality and evolving character. 
 
Liefeld should be happy anyone even knows who  Shatterstar is.

How on earth is he being "held back"..??

Shatterstar's actually been TALKING and DOING things in a comic book nowadays, as opposed to languishing in limbo or just being a killing machine with zero personality (because writers don't know what to do with that Benjamin Russell hot mess).

It's not like Peter David just gives Shatterstar make out sessions with Rictor. He has LOL "American culture shock" lines, kickass fight scenes, as well as revealing conversations with Rahne, Monet & others. Plus, he's now the X-Factor teleporter.

Perhaps you just prefer a mysterious, macho, gladiator type with a long, flowing ponytail wearing big shoulder pads. Gee that sounds rather... gay.