Most systems don't need to scale beyond "please no obvious performance bugs", so it makes sense to write most applications as monoliths for the reason that you are stating (i.e. development is faster).

It only makes sense to write services (note, "services", not "micro-services") when it is inevitable and obvious that your software is hitting scaling issues related to some subsystem, or when you have systems that need to be independently reliable. (i.e. ATM's should work even when the banks website is down)