Just a few quick observations;
Fr. RK is retired now hence he may not care as much about the mass stipends especially if they are included in his salary and maybe his retirement as it has been a practice in some dioceses. However, we must not forget that in most dioceses priests receive very poor salaries in comparison to other ministers. Many priests with PhD and DMin and other academic degrees make  no more than $45,000 a year after 50 years of service. Even if we include room and board, it is still a joke in comparison to the bishops who have endless access to diocesan money that often lack public disclosure and transparency.
The sacrifice of the Mass should be a sacrifice and making a $5 or $10 dollar donation does not break a bank especially for the folks living in the First World Countries. If people can not afford it than waive the fee.
Let’s talk about more pressing issues like Catholics leaving the church, women being treated as 2nd class members and the clerical culture.