Coming from a server owner perspective (I own a small network which has been in maintenance for a few months).
Having many mini-games requires A LOT of work. Developing your own game requires intensive time and effort. Getting plugins of Bukkit/Spigot would also take a while if you truly want to make it your own.
Basically all I am saying is.
MCGamer has lots of players, lots of staff and lots of drama (Like every big server). This means that effort and time are put into different things in order to keep the network running internally.
TIS HARD STUFF YO