What has happened to today's chicken compared to the chicken in the 1950's - 80's?
I don't think much has happened to washing a chicken in itself, rather much more has happened to our knowledge about bacteria, hygiene, and cross contamination. 

Most likely, with or without washing, nothing bad is going to happen. But then again: It might. 
Properly cooking the poultry is going to get rid of the bacteria on the chicken, no washing needed. With washing, bacteria present on the chicken might spread to other parts of the kitchen and ingredients, and some of that might be consumed raw, or not cooked through &amp; through, increasing the risk of contamination.

Personally, I'm not overly worried about getting infected, and I never have been, but I might, you might, and you wouldn't want guests to be. It's risk reduction, rather than anything else.