Better nutrition, hygiene, antibiotics and I believe - vaccinations have all contributed to a lessening of these problems. A more serious, but fortunately much less common complication is brain thickening or sclerosis which occurs after months or several years following measles. Although not strictly true it may be thought of as a dementia. Measles vaccinations are said to prevent this. Another danger of measles is that it can be misdiagnosed as rubella, as symptoms can look the same.
Vaccinations are also a way of protecting pregnant women from getting it.
However, measles is one of the most transmissible viruses and outbreaks can and do occur even when a large proportion of the community are immunised. Indeed, many countries routinely give all children two doses of measles vaccine. Published material shows that re-immunisation is safe. Using presently available vaccines in older age group children, we can be confident that any convulsions are going to be exceptionally rare if they occur at all. There is no realistic alternative to prevent this huge burden of illness and death other than immunisation.