I think you're making two separate points.
To the first point - the reason you're unable to get very far in Hydra is because you're simply not at the point in the game Hydra is intended for. Hydra is meant for late-game players who have had top UNM chest on farm for a while, have all of DT normal cleared easily, and likely have most if not all of DT hard cleared. Critically, it's also intended for people who have a *very* large stable of champs to choose from - personally, I have over 100 level 60's, most of which are geared, which allows me to find the right teams for several keys worth.
To the second point - hydra not being fun is likely in part caused by the above, but yes, there are many issues with hydra. Personally I hated it for the longest time, but now that I've seen how good Mithrala is for arena, I've been just forcing myself to do it, and the more I do, the more enjoyable it gets as I start to understand the mechanics.