Sorry for giving you that kind of impression.
Oh my. You are not wrong for enjoying this game - go ahead and play! Have fun! =)
It's just my opinion, nothing more. Don't get me wrong, I played through the story mode and some Adventure mode missions with a friend. I played every character with every weapon, saw every cutscene, saw every special and slashed through more than enough enemys.
And it was quite fun together!
But it's getting old to fast. But why does it feel this way? The gameplay is nice, the graphics are ok for the WiiU and your slashes gives you real good feedback that you kick ass. Easy: Cause the game has no variety - every mode contains the same. And you can give me 100 of these 8-bit maps - they're still only little packages with more missions on the same battlefields with the same enemys.
This is no good design for a game of that genre.
Take Bayonetta for example: It's "just" hack and slash and could have ended up the same way. But it did not. Because the developers did an awesome job outside of their battle system. Very different spots to travel to, great and exciting unlockables, great characters, sense of humour, mini games, riding and flying missions and AWESOME DESIGNED BOSSFIGHTS. You definitly can't complain about variety here.
There are so many ideas in Hyrule Warriors that they did not think through to the end, but implented them halfway and throw the game out.
And here one must see the game for what it is. A not so good Dynasty Warrior taking a ride on the Zelda franchise, with wasted potential. You have fun, I had fun too. But I don't close my eyes before the great game that could have been made.
And for that part: You're absolutely right - no one is forcing me to do this. On the other side I need it to unlock certain things like new potions and a tunic as far as I know. This is game time stretching and totally unecessary.
For the record: Having fun with a game and seeing the weak parts of a game is both possible.
Or love the game over everything else and get an even weaker sequel - cause everything is perfect, isnt it?