Low water fishing can be very easy. My river often gets so low floating is impossible in late summer, and the smallies drop back into winter holes to find enough water for protective cover. They don't avoid current, but rapids and riffles are so shallow big fish stay out of them.
As for long term impacts, yes, low water can be every bit as bad as high water on the survival of fry after the spawn. Years with drought low flows all summer often have almost no recruitment of fry spawned that spring. Several years of low flow consecutively can negatively impact the fishing 4-5 years down the road, as can consecutive years of high flows in spring.
Also, with the quality fish so concentrated, high water temps, and often low dissolved oxygen levels, the fish are easier to stress, and easier to catch if you can avoid spooking them. That combination can mean fishing pressure can have more impact on mature fish, although usually if the river is drought low, fewer people want to go on a paddle trip, err I mean hike, down the river.