Firstly, you can’t say that “…my property value has not increased and may actually decrease in the near future…therefore my MR should be tax deductible…”. It doesn’t work that way.
Secondly, public facilities (library, park, school, etc.) built using the MR money is typically intended mostly for residences of that particular community, not all San Diegans. I, living in Santee, would not send my kids to school in SEH, would not have a casual pick nick at De Sur’s park and would not be checking books from 4S Ranch’s library. These facilities are enjoyed almost exclusively by the residences of these master planned communities.
Where I live (Riverwalk of Santee), YMCA and city-owned sports park are just across the street. Nearby schools & libraries are for all residences of Santee. The community is not so far away as to needing a lot of infrastructure improvement to be connected to the city. Thus it’s one of the very few large new housing community in Santee that doesn’t have MR.