I agree 100%.
I like BF for the variety. I play a mix of large and small map game modes, objective modes the lot. Overall I am not very impressed with Redsec. The gauntlet mode is OK, but again, nothing to get too excited about. 
I'm very disappointed, like you, that more that half of my challenges were for the new BR type modes that I don't really want to play... I think they will turn players away if they're forcing them into specific modes etc
And to add to the disappointment, there's a bug where if you have a challenge tracked, you can't reroll it, but if you try, it will still cost you a reroll token... (yet ANOTHER bug with tracked challenges.. )
On 'the other game' when they've had seasonal events etc, they've often had challenges you can progress by either playing MP, Zombies or WZ. I think this is a much better system.
#DicePlease. Let people play what they want to play!