Here's what I know regarding Freebuild:
Factions was left with a game-breaking bug for six months. Said bug was the result of the /sethome command, which when inputted would instantly crash the server and reset it by about five minutes or so. A friend of mine contacted Marco personally and explained the issue, yet he was adamant on not fixing it. The problem persisted for over six months or so, until the server was eventually taken offline alongside the rest of Freebuild.
We were told in early 2015 that it would be returning. I believe that this was their original intention, seeing as how there were staff-endorsed suggestion threads, and additions to the 'Factions' section of the forums. However, as each month passed, we were repeatedly told that it would be coming 'Soon'. A few ETA's they gave were Summer 2015, Fall 2015, "the end of the year", and Summer 2016. Since then, we've heard nothing, and the spawn that was intended to be used for Factions was re-purposed for something else.
Whatever their reasons for this, it's evident that the management team does not want Factions on the server. Keep in mind that a simple change of rank permissions would've resolved the bug, thereby allowing its still sizable player-base to enjoy the game. For whatever reason, they decided to dismiss all requests to do this. I can therefore only conclude that they do not want Factions on Cubecraft.
In relation to Skyblock, a game-breaking duplication glitch was found and exploited at a very inconvenient time, being when Rubik_Cube_Man was I believe on vacation. By the time anything could be done, the game's integrity had long since shattered. Shortly thereafter, the world corrupted and the server went offline. It was revived, however due to the immense player-count, it shortly became unplayable again, the world corrupted, and the game was swiftly removed.
Despite the evident demand for its return, the management team likely feels it's too risky an investment due to these two aforementioned experiences.
It's a shame to see how all those who once advocated for the return of these once beloved games have long since quit, no doubt out of impatience or frustration.
The only advice I can give to you if you're expecting to see them, is to not get your hopes too high. Perhaps they'll surprise us someday and we'll see them return, but from experience, I sadly wouldn't count on it. Skyblock may still return (fingers crossed), however Cubecraft Games is a minigame server now, and is no longer known for hosting Freebuild games.