It's more problematic from the side of it being the last season of MLP. I had no problems with Discord turning soft, because we knew it wasn't a finale.
I loved the way that Starlight turned soft (and honestly think that this is where MLP should end, since "Cutie Re-mark" was such a fantastic way to end the series)
But this time, it's our last season and we should get at least one villian who seems at least semi threatning. It should be loud and epic way to end the show. It will be hard to be more epic than Twilight's Kingdom, but it's possible.
I kinda feel like they are trying to downplay Tirek for people to not compare him to Grogar. As far as we have seen, Tirek is much more powerfull than Grogar. I think that we ethier should have Sombra return for the finalie, as he was probably the last "serious" villan we had. He also needs desperatly a "redemption arch".
We could have then have Sombra, Cozy, Tirek and Chryssi team up on Grogar.