One thing about replacing (or not replacing) lower-tier cranksets;
I have come to really like cranksets having a pants leg protector ring. I sometimes go to some length getting such rings to run true, even though that's not always as easy as it sounds.
Being able to jump on a bike without changing out of my lightweight trousers is how I get in about half of my rides these days, finding a hole in the rain forecast and/or making an errands run on any of the lesser bikes (i.e. the ones with such chainring guards and that can be left briefly unattended in public places).
Luckily I live in quite hilly terrain so even a short ride can involve challenging hills so I'm able to maintain some critical muscle mass despite an often busy schedule and/or iffy weather (today = Exhibit A and I've got to get back in time to watch the Daytona Supercross).
I'll try to update this post with a couple of photos of a typical such riding scenario (rain starts in three hours, so give me a couple of hours, lol).