No, it’s not.
Still a bad idea.
If they allowed grinding CCs in single-player via challenges, they would have to make challenges a lot harder, so you can’t cheese them. And you know what’s Funcom idea of “harder”, right? They don’t make things challenging, they make them longer to complete, i.e. more boring.
I’m thankful for the opportunity they gave us to do BP challenges in single-player, because sometimes a challenge will pop up that can’t even be done in Exiled Lands (and they don’t give a shіt about fixing that, apparently), or doing it involves spending resources on crafting yet another copy of a thing I don’t need a million copies of, or something equally boring/useless/buggy/cumbersome.
In short, being able to do challenges in single-player is what allows me to compensate for Funcom’s apparent inability to make their challenges fun and engaging. I don’t want to lose that just because people want to buy overpriced cosmetics from the BLB shop but don’t want to pay money for it.
If you think BLB is overpriced – which I wholeheartedly agree with – the solution is not to ask for free CC handouts, the solution is to not buy spend the money on it and let Funcom know why. If that makes them fix the prices, so much the better. If it doesn’t, it means their monetization strategy is working out for them and you can’t compete with the whales.