It's completely true that we get to focus on the fun parts, but I think the burnout some of us are feeling is that the boring parts were also protecting us. It wasn't always fun to spend an afternoon mapping out a 500 line python class; but it sure was relaxing, and a good reason for deadlines to shift forwards and back by a day or two when they needed to. Now we only do the fun parts, which also are all of the least well-specified tasks, the parts that require 100% of our brains, the people-focused parts, and the most time-sensitive parts. All things which leave us tired at the end of the day, even if they are fun. Not to mention the 5-10x increase in context switching, which is itself draining.
Perhaps we'll work out new norms for how to organize our time sustainably. Or perhaps ClaudeCodex will finish blowing through the job of a SWE in the next 24 months (remember, it's only really 12 months old in its current form).