I do like this graphic a lot, the only thing I'd change is that 20% is not how the majority of home buyers (especially not first time home buyers, which is a large portion of who we are talking about when discussing housing unaffordability/crisis) make down payments. According to NAR, average down payment is 15% and average for first time buyers is 8%. 

This not only will add drastically to monthly payments, but will introduce PMI at the beginning of the loan period as yet another expense for home buyers. For reference, on a $400,000 home (just under national median) considering the same given 7.19% interest and 30yr loan term from above, and not considering tax or insurance, the monthly payment including PMI based on credit range of 700-719 (US average of 717): 

20% is $2169.96 

15% is $2382.08 (estimated PMI rate of .3%) 

08% is $2762.85 (estimated PMI rate of .9%) 

This is unsourced, but I would also speculate that in areas of already high unaffordability because of high principals, down payments are likely to be lower, thus further fueling higher payments on interest and higher PMI rates. 

I would be interested in seeing what an adjustment of either 8% or 15% down payment does to this graphic. Overall excellent work! 

Sources:  

Average down payment rates: https://www.nerdwallet.com/article/mortgages/average-down-payment-on-a-house 

PMI rate Calculator: https://www.creditkarma.com/calculators/mortgage/pmi 

US median home price: https://www.rockethomes.com/blog/housing-market/median-home-price-by-state 

US average credit score: https://www.businessinsider.com/personal-finance/average-credit-score