If you are coming to the Philippines to live here, having some kind of health insurance is a good idea. You need to be protected from the high cost of being sick. Getting sick can really bankrupt you these days.
Fortunately, there are some advantages about the Philippines, though. Primarily, the cost of health care in the Philippines is quite low. For many cases you can self-insure here in the Philippines, because for the vast majority of services, the cost is small enough that it can be paid out of pocket.
However, if you have a major medical issue - cancer, heart attack, something along those lines, self insurance won't be a good answer, unless your savings are substantial. In that case, having some kind of health insurance is highly advisable.
What if you are just here for vacation though?
Many people would avail of Travel Insurance to fill the gap in coverage during their overseas vacation. Others may just go uninsured during that time - the risk is quite small after all.