That's the "You need to buy a chainsaw!" bug... it's quite common in trees that have been neglected and dying for years. They emerge from their pupae stage just in time to admire the look on a homeowner's face when they suddenly realize that trees actually need some attention before they are near death.
I would suggest that you do some research on tree species that are low maintenance and do well in your part of California, and whose mature size fits your space requirements. Local nurseries, county extension offices, forestry departments, etc. can all give you advice and help with selecting trees that will thrive in your area and conditions. None of the trees you select will be completely maintenance free... they need frequent inspection and care to keep them healthy and catch problems before they get out of hand.
The trees you've posted pictures of in this and the other thread are pretty much beyond help.