You see, when Mello-Roos was enacted, I felt the same as you, that this was a burdensome and unnecessary tax. However, we have discovered that IF you have children of school age, or you are planning to rent or sell to someone who has children of school age, then the Mello-Roos school is very valuable. It is then very very desireable.
Mello-Roos schools have no restrictions on how they can spend their budget. If they want to buy computers instead of books, ok. If they want to hire a teacher instead of a janitor or administrator, ok. If they want to fix the roof instead of buying furniture, ok. You see, this has made it possible for Mello Roos schools to be as good as private school for education at a fraction of the cost.
Public schools not under Mello Roos cannot buy computers instead of books, or hire a teacher instead of a janitor or administrator, or take a field trip instead of buying lunch. The state and county schools have fixed budgets for everything, and they cannot be applied to anything else. This has made public schools not under Mello Roos very inflexible, and frustrating for teachers, administrators, parents and students. Mello Roos is a very good thing, and a bargain if you, or your tenants, or the buyer of your home have school age children and want a very very good education for them at a very good price.