Yes, that's because Warsaw is just the major city and capital, a modern city totally rebuilt after the war, so there really isn't anything unique about it other some historical significance. Krakow wasn't damaged during the war so there is a lot of old architecture to see and it isn't such a busy working or administrative city so much less hectic or polluted. I would disagree with only of your comments, that "food is generally good". Traditional Polish food is really not good at all, much like most in that region mostly some combination cabbage or potatoes and poor quality meats.
Kraków is a beautiful city, highly recommended. Warsaw is nowhere near as beautiful as Kraków, half a day around the old town and IF the weather is good a couple of cocktails around the river bank bars will do. Take the morning fast train from Kraków for about £20 first class and in 2 hours you will be in Warsaw, spend the day there, pick the evening train back and you will be fully sorted. Poland is generally very cheap (excluding museums), food is generally good, transport is also very reasonable (uber for city transports is cheaper than a bus ticker in the UK, Warsaw centre to Modlin is about 120 zloty/£25).
I too have just returned from Kraków a beautiful city ... Every thing is cheap ... uber taxis operate here... eat in the local milk bars .. sip cocktails in the square and beware of the fire breathing dragon ! We stayed in a beautiful apartment in the Jewish quarter -10 mins from the old town on foot ... ... a must go city !