Whether Cyborg was on a team previously or not makes no difference. The problems are simply there with the character. What I suspect is if the character had success as a solo character, which is unlikely given, again, he supplies no wish fulfillment whatsoever, then there would be a segment of fans more accepting of him being on the Justice League and getting his push based on that. So he would have more legitimacy if he could carry a solo series... which he can't. Which hurts his legitimacy, because every other main Justice League character can.
But the... "Cyborg is fundamentally flawed for being DC's premier black male character when you compare him to his peers," and "Put Cyborg back on the Titans and restore his history with them, I liked him how he was before," are two totally different discussions. Interestingly, they're both often points of discontent readers have with the character. He seems to get far more criticism than praise, yet DC doesn't do much to address issues people have with him. I guess they have him pal around with Starfire now, which may appease the people who like him to hang out with Titans.