How about not having to put a needle into a child more times than necessary?
How about the fact that a lot of people have busy lives and it is often difficult enough for them to find the time to come in for normal vaccination schedule without adding to it?
As well, all countries except for the USA have completely different health care systems with different methods of payment for immunisation, so your argument actually supports the MMR.
In every single other country where doctors are more likely to be rewarded by outcomes, not the number of procedures, as in the USA.
Financially, doctors and insurance companies would prefer more jabs than fewer jabs.
Do you realise the number of potential pathogens we encounter every single day?
Just about everything is covered in foecal coliforms as well as other bacteria.
This doesn't even include the number of viruses or fungal spores our bodies deal with every single day.
Three inactivated viruses is a cake walk for our immune system.
http://www.webmd.com/news/20070625/top-spots-for-bacteria-at-home