Reason for that is very simple, GF just do not see Gladiatus like profitable enough to put more they time and money in development that game. Even there is not Gladaitus on they official page....
One of the biggest reason why they kept Gladaitus "alive" because is cheap to maintain.
But I think that Gladaitus will develop over time but very slowly...
I do not judge GF for that because they are just a firm that must think about they profit which is needed to pay workers and all other costs.... but I judge them maybe only because they promise things that they did not (or cannot) fulfil.
This is true, but on the other hand we (as in players) feel more and more cheated each day, we put time and money into the game so GF should do the same. This is such an old game with such an old "engine" that there is no need for a big development team, 2-3 people could easily maintain the game, but GF doesn't even want to do that. Once, twice a year they give some developer 2-4 tasks to do that take couple of days and then they release them in batches to make it look like they're working on something, which in reality is pure BS.
They should've closed the game long time ago like they did to metal-damage, or they should've sold it like they did with BiteFight.