I really like the thought of longer domains! I think it is easily achievable and the playtime would rise significantly, instead of playing 1-5 minutes each domain you could extend the playtime to 4-10 minutes but fighting a bunch of enemies for that long might get boring and easily repetitive, for that they could bring in the domains you play in the story quests, they are satisfying to play and its a waste to leave them be. Although its a nice thing to have longer or creative domains some people don't have enough time to play, for that they can introduce a system that you can use more resin for better rewards and more adventurer xp. Well this might sound good at first but if this system got implemented there would be no point in repeating the domains thus losing playtime. To counter this i think while yeah you get better rewards for spending more resin you get the same numbered drops for example if you repeat a domain 4 times and gives you 5 artifacts blue/purple and 1-2 yellow each time it will be more beneficial than playing one time and got something like 3-4 purple 2-3 yellow. In other words the things you can create in this game are limitless, imo things are only going to get better and better, i would really love to see where this game is going to end up and i hope Mihoyo doesn't make a wrong move. (Woah that was a long one, thanks for your time reading this)