Uhhmm How many times Aquaman or Green Arrow has been canceled? When has Martian Manhunter hold been able keep a book? Lets not go popularity and commercial success because publishers have a history of torpedoing books with questionable choices and while keep characters in spotlight even though they are struggling because of their back catalog. Cyborg is inline with other choices that is on the team. Consistently give Cyborg the creative teams that Batman and Superman get lets see if he won't have commercial success. And while we are on Batman and Superman how about they tone ridiculous love of them other characters can look like amazing heroes. Good luck Cyborg being written as smart tech guy with Batman around. Cyborg can easily be written as one of the smartest characters in DC and the go to for all thing science/tech related but BatGod needs his moments. Another easy example is a character like Damage who is designed to be a strength monster, Good Luck convincing fan base or even writers to write a character stronger than Superman. Let not pretend there is a system that keeps characters from shining and being a top hero.
It is funny that you mention Wolverine and Spiderman, Avengers switches between Classic roster and A-listers. Marvel had a period where they went you know what the Avengers should be "The Justice League" aka the biggest heroes the A-listers and guess what Wolverine,Hulk,Dr Strange and Spiderman are in that group but in weird reversal of DC fans,Marvel fans seem want a more classic line up which isn't necessarily all the big guns. Which brings me to point that reverse is happening here some fans are asking that Justice League not be always made of the "Big Guns" and DC case "The Big guns" is this team isn't very dynamic and versatile powerset wise and it lacks diversity. DC more than Marvel has reason to move away from the classic team. The most annoying thing is new characters or even some of the older ones aren't allowed to be "A Big gun". DC is having a big event where heroes get a chance to shine as "Big Gun" If Cyborg isn't on the main team in the main story with significant role,How does he become a Big gun? .
I thought that DC putting Cyborg in Justice League mean he would be treated like a equal member getting story arc on him and moments to shine, They would put star creative teams on his solo book(they did at beginning), They would give him animated movies. That is not how it played out. He was transport and exposition machine and when his solo book need to be refocus like all characters they didn't use star creative teams again. I am tired of people saying characters aren't star quality but they keep throwing C level creative talent and expect A level results while they keep throwing A-list caliber pencilers and writers at main Superman and Batman books. To often the effort does not match the intent and they would give Wonder woman and Superman tons of chances to refocus and find a path that works but I watch Static or Blue Beetle just canceled never to been seen for years.