Yes the rewards do get better, Monster drops get better & Leyline rewards increases. Here is the thing if you don't ascend you can't access higher level domains, which have 5-star items. Instead you end up wasting resin on 4-star items which become useless later own. Need stronger items to get stronger. But you need to be already strong to get
Personally, I'm not struggling in the content but I have friends who are. You could even drop your world level, and as a result, your characters/weapons will temporarily drop to the max allowed at that certain world level. This can be beneficial to co-op too, so lower level friends can join your world (for some reason I can't think of). zTXlI.