New Redemption Grab Bag now includes an assortment of 500 cards from five (5) different expansion sets. Available at Cactus website.
The artifact you leave up is the artifact you activated, doesn't seem too convoluted. Like if you miss an optional trigger, you can't go back it's just assumed you passed. It's much more complicated to retrain everyone to formally announce their artifact activation, because most people are not in the habit of doing that. But if captured ark isn't treated this way, to be consistent, how would you suggest treating three nails? I leave three nails up but don't activate it and my opponent doesn't block with demons because he thinks it's active. Yet on his turn I can block with demons because I didn't activate it?
The rule that they activate each prep phase has been around since Priests.
You're splitting hairs here with language like "intentionally activated"; no such terminology in redemption exists. Ongoing or not, artifacts still have to activate to take effect. So advocating for ongoing artifacts to automatically take effect when flipped up but requiring an announcement for upon activation artifacts actually make artifact interactions more convoluted and inconsistent.